Storage System and Method of Managing Data Using Same

CROSS REFERENCES

0001This application relates to and claims priority from Japanese Patent Application No. 2007-142491, filed on May 29, 2007, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

00021. Technical Field

0003The present invention generally relates to a storage system and a data management method executed in this storage system, and particularly relates to backup/restore technology of data in a SAN/NAS integrated storage system.

00042. Description of the Related Art

0005In a computer system, it is standard to back up data stored in a storage subsystem periodically or irregularly so that data can be restored immediately even when such data is lost due to a failure in the storage subsystem or the like.

0006From the perspective of temporal transition of volumes storing data, the backup of such data may be classified into a full backup method of backing up the entire data as the backup target, and a differential backup method of backing up the updated (differential) portion with the fully backed up data as the origin.

0007Japanese Patent Laid-Open Publication No. 2005-122611 discloses technology of selecting the optimized backup method; that is, either the full backup method or the differential backup method, in which the recovery of data within the target recovery time designated by the user is expected to be possible based on the restoration performance of a backup target volume and the update quantity of data in such volume.

0008Further, from the perspective of data structure, backup may be classified into a file backup method and a volume backup method. With the file backup method, for instance, backup is performed in directory/file units configuring a file system managed by NAS (Network Attached Storage). In contrast, with the volume backup method, for instance, backup is performed in volume (logical device) units configured in a storage subsystem. Because the volume backup method copies the binary data of the volume itself by using the implemented function in the storage subsystem, there is an advantage in the execution performance in that the backup processing is faster in comparison to the file backup method.

0009Further, with a typical SAN/NAS integrated storage system, the host apparatus accesses the storage resource (i.e., data) in a SAN-connected storage subsystem via a NAS apparatus (i.e., a file server). Thus, the file backup method is considered to be more compatible with the backup of data in the SAN/NAS integrated storage system because it is able to select the backup target in units of files.

0010Further, Japanese Patent Laid-Open Publication No. 2004-259045 discloses technology of backing up data in a tape device to which a NAS volume is SAN-connected in a SAN/NAS integrated storage apparatus.

0011With the file backup method, the user (system administrator) may selectively designate the backup target in file units. However, the NAS device needs to process the structural data concerning the file system during backup processing. Thus, the execution performance of the system becomes relatively low. Also, a CPU and/or network system gets overloaded.

0012With the volume backup method, although the execution performance is relatively high, the storage cost is high since a volume is used as the unit of a backup target.

0013Thus, for example, in a case when the directories of the backup target are consolidated into a single volume, there are cases where the execution performance would be higher by selecting the volume backup method rather than selecting the file backup method. However, since it is difficult for the system administrator to recognize what kind of logical volumes are configuring the storage resource in the SAN/NAS integrated storage system, it is also difficult to select the appropriate backup method.

0014Moreover, in recent years, a SAN-connected storage subsystem is mounted with various sophisticated copy functions such as remote copy, journaling, and snapshot. However, even if this kind of SAN-connected storage system is incorporated into a SAN/NAS integrated storage system, there is a problem in that these sophisticated copy functions cannot be effectively utilized.

SUMMARY

0015An object of the present invention is to enhance the efficiency of backup/recovery processing by giving consideration to the balance between the effective performance of backup/recovery processing and the storage cost in the storage system.

0016More specifically, an object of the present invention is to enable the storage system to select the optimal backup method for backing up a directory designated as the backup target.

0017Another object of the present invention is to enable the presentation of the selected backup method to the system administrator.

0018Further, another object of the present invention is to enable the backup processing to be executed according to the selected backup method.

0019Furthermore, another object of the present invention is to enable the recovery of backup data based on the backup processing executed according to the selected backup method.

0020In order to achieve the foregoing objects, the present invention provides the following subject matter sought to be patented.

0021The present invention provides a storage system and a data management method in such a storage system that acquires directory configuration information concerning a directory designated as a backup target, and executes backup processing according to an optimal backup method to the designated directory based on the acquired directory configuration information.

0022Specifically, According to an aspect of the present invention, the present invention provides a storage system comprising a file server operatively connected to a host apparatus and configured to provide a directory in at least one file system having a directory structure to the host apparatus, a storage subsystem operatively connected to the file server and configured to provide at least one volume for storing the at least one file system, and a management apparatus operatively connected respectively to the file server and the storage subsystem and configured to manage backup/restoration of an arbitrary directory contained in the at least one file system. The storage system comprises a backup controller configured to select one of prescribed backup methods to a directory designated as a backup target by the management apparatus based on directory configuration information of a file system regarding the designated directory, and to execute backup processing to the designated directory according to the selected backup method.

0023Further, according to another aspect of the present invention, the present invention provides a storage system comprising a file server operatively connected to a host apparatus and configured to provide a directory in at least one file system having a directory structure to the host apparatus, a storage subsystem operatively connected to the file server and configured to provide at least one volume for storing the at least one file system, and a management apparatus operatively connected respectively to the file server and the storage subsystem and configured to manage backup/restoration of an arbitrary directory contained in the at least one file system. The file server selects one of prescribed backup methods to a directory designated as a backup target by the management apparatus based on directory configuration information of a file system regarding the designated directory, and sends the selected prescribed backup method to the management apparatus. The management apparatus provides the selected backup method to a user, and causes either the file server or the storage subsystem to execute backup processing based on an execution command from the user.

0024Moreover, according to another aspect of the present invention, the present invention provides a method of managing data in a storage apparatus including a file server that provides at least one file system having a directory structure in a volume formed in a storage subsystem to a host apparatus. This data management method comprises receiving, under control of a management apparatus, a designation of a directory to become a backup target in the at least one file system, acquiring, under control of a backup controller, directory configuration information of a file system concerning the designated directory, selecting, under control of the backup controller, one of prescribed backup methods based on the acquired directory configuration information, and executing, under control of the backup controller, backup processing to the designated directory according to the selected backup method.

0025According to the present invention, it is possible to efficiently back up the data stored in the storage subsystem.

0026In particular, according to the present invention, efficient backup processing is executed since either the file backup method or the volume backup method is selected according to the directory configuration information of the directory as the backup target upon backing up the directory/file in a SAN/NAS integrated storage system.

DESCRIPTION OF DRAWINGS

0027<figref idref="DRAWINGS">FIG. 1</figref> is a conceptual diagram explaining a data backup/restoration mechanism according to the present invention;

0028<figref idref="DRAWINGS">FIG. 2</figref> is a diagram showing a schematic configuration of a computer system according to the present invention;

0029<figref idref="DRAWINGS">FIG. 3</figref> is a diagram explaining a configuration of a NAS device according to an embodiment of the present invention;

0030<figref idref="DRAWINGS">FIG. 4</figref> is a diagram explaining a configuration of a storage subsystem according to an embodiment of the present invention;

0031<figref idref="DRAWINGS">FIG. 5</figref> is a diagram explaining a configuration of a management apparatus according to an embodiment of the present invention;

0032<figref idref="DRAWINGS">FIG. 6</figref> is a diagram explaining an example of backup history information according to an embodiment of the present invention;

0033<figref idref="DRAWINGS">FIG. 7A</figref> and <figref idref="DRAWINGS">FIG. 7B</figref> are diagrams explaining the directory-volume correspondence relation according to an embodiment of the present invention;

0034<figref idref="DRAWINGS">FIG. 8</figref> is a diagram explaining an exemplary volume configuration information according to an embodiment of the present invention;

0035<figref idref="DRAWINGS">FIG. 9</figref> is a diagram explaining an exemplary directory configuration information according to an embodiment of the present invention;

0036<figref idref="DRAWINGS">FIG. 10</figref> is a schematic flowchart explaining backup processing in a storage system according to an embodiment of the present invention;

0037<figref idref="DRAWINGS">FIG. 11A</figref> and <figref idref="DRAWINGS">FIG. 11B</figref> are diagrams explaining an example of a backup wizard screen according to an embodiment of the present invention;

0038<figref idref="DRAWINGS">FIG. 12</figref> is a diagram explaining backup method selection processing in a NAS device according to an embodiment of the present invention;

0039<figref idref="DRAWINGS">FIG. 13</figref> is a schematic flowchart explaining restoration processing in a storage system according to an embodiment of the present invention;

0040<figref idref="DRAWINGS">FIG. 14A</figref> and <figref idref="DRAWINGS">FIG. 14B</figref> are diagrams explaining an exemplary a restoration wizard screen according to an embodiment of the present invention;

0041<figref idref="DRAWINGS">FIG. 15</figref> is a flowchart explaining restoration data selection processing in a management apparatus according to an embodiment of the present invention;

0042<figref idref="DRAWINGS">FIG. 16</figref> is a flowchart explaining restoration processing in a NAS device according to an embodiment of the present invention;

0043<figref idref="DRAWINGS">FIG. 17</figref> is a flowchart explaining restoration processing in a NAS device according to an embodiment of the present invention;

0044<figref idref="DRAWINGS">FIG. 18</figref> is a conceptual diagram explaining restoration processing in a NAS device according to an embodiment of the present invention;

0045<figref idref="DRAWINGS">FIG. 19</figref> is a diagram explaining a modified example of a storage system according to an embodiment of the present invention; and

0046<figref idref="DRAWINGS">FIG. 20</figref> is a diagram showing a configuration of a computer system according to another embodiment of the present invention.

DETAILED DESCRIPTION

0047Embodiments of the present invention are now explained with reference to the attached drawings.

0048<figref idref="DRAWINGS">FIG. 1</figref> is a conceptual diagram explaining a data backup/restoration mechanism according to the present invention. It will be apparent to one skilled in the art that backup and restoration are of a complementary relationship, and as used herein, the term “backup” may include “restoration” unless otherwise stated.

0049As shown in <figref idref="DRAWINGS">FIG. 1</figref>, a storage system <b>10</b> according to the present invention is configured by combining a NAS device <b>11</b> and a storage subsystem <b>12</b>. The NAS device <b>11</b> and the storage subsystem <b>12</b>, for instance, are connected via a SAN. The storage system <b>10</b> also comprises a management apparatus <b>13</b>.

0050Although the NAS device <b>11</b> is generally a file server itself, as referred to herein, it shall be a server mounted with a dedicated OS specializing in file services. The NAS device <b>11</b> is typically mounted with a file backup function. The file backup function is a function for backing up data in shared directory/file units. Further, the NAS device <b>11</b> of this embodiment, as described later, is configured to provide the optimal backup method to a system administrator using the management apparatus <b>13</b>.

0051The storage subsystem <b>12</b> is configured to include a disk array device as a physical storage device. The storage subsystem <b>12</b> provides a logical volume or a logical unit (hereinafter referred to as a “volume”) formed in the disk array device to the NAS device <b>11</b>. In other words, a volume is a logical storage device to be recognized by the NAS device <b>11</b>. The storage subsystem <b>12</b> is typically mounted with a volume backup function. The volume backup function is a function for backing up data in volume units.

0052Let it be assumed that the NAS device <b>11</b> currently contains file systems A and B. The file system A has a directory structure containing “dir0” as a root directory, and dir<b>1</b> and dir<b>2</b> formed as lower directories thereunder. Further, the file system B has a directory structure having “dir3” mounted on the root directory “dir0” as its highest-level layer, and “dir4” to “dir6” formed as lower directories thereunder.

0053Further, the storage subsystem <b>12</b> has volumes VOL<b>0</b> to VOL<b>2</b> formed therein. The overall file system A is formed in the volume VOL<b>0</b>, and the overall file system B is formed in the volumes VOL<b>1</b> and VOL<b>2</b>.

0054With the storage system <b>10</b> having this kind of physical/logical configuration, when backing up the overall file system A, it is apparent that the volume VOLO can be backed up using the volume backup function of the storage subsystem <b>12</b>. Likewise, the volume backup function may also be used when backing up the overall file system B. In general, since the volume backup method is more advantageous in terms of effective performance in comparison to the file backup method, in the foregoing case, a more efficient backup can be expected by using the volume backup method.

0055In contrast, for instance, when backing up “dir6” of the file system B, using the volume backup function would be inefficient from the perspective of storage costs. Therefore, in the foregoing case, the file backup function of the NAS device <b>11</b> is used to backup “dir7.”

0056Thus, the storage system <b>10</b> selects the optimal backup method to a directory as the backup target, and provides the selected method to the system administrator operating the management apparatus <b>13</b>. The system administrator confirms the selected backup method via the management apparatus <b>13</b>, and thereby the storage system <b>10</b> executes backup processing according to the selected backup method.

0057<figref idref="DRAWINGS">FIG. 2</figref> shows a schematic configuration of a computer system according to an embodiment according to the present invention. As shown in <figref idref="DRAWINGS">FIG. 2</figref>, the computer system <b>1</b> comprises one or more NAS devices <b>11</b> connected to a host apparatus <b>3</b> via a network <b>2</b>A, and a storage subsystem <b>12</b> connected to the NAS device <b>11</b> via a network <b>2</b>B. In other words, the storage system <b>10</b> is connected to the host apparatus <b>3</b> via the network <b>2</b>A, and the host apparatus <b>3</b> accesses the volume VOL under the control of the NAS device <b>11</b>. The computer system <b>1</b> also comprises a management apparatus <b>13</b> respectively connected to the NAS device <b>11</b> and the storage subsystem <b>12</b>.

0058The network <b>2</b>A, for instance, is a LAN or the Internet. Further, the network <b>2</b>B, for instance, is a SAN. In this embodiment, the network <b>2</b>A is configured from a LAN based on a TCP/IP protocol, and the network <b>2</b>B is configured from a SAN (FC-SAN) based on a fibre channel protocol.

0059The host apparatus <b>3</b>, for example, is a core computer in a business system of banks or a seat reservation business system of airline companies. Specifically, the host apparatus <b>3</b> comprises hardware resources such as a processor, a memory, a communication interface, a local I/O device and the like, and also comprises software resources such as a device driver, an operating system (OS), an application program and the like (not shown). By way of this, the host apparatus <b>3</b> executes various programs under the control of the processor, and realizes desired processing based on the cooperative effect with the hardware resources. For example, the host apparatus <b>3</b> accesses the storage system <b>10</b> and realizes a desired business system by executing business application programs based on the OS and under the control of the processor.

0060The NAS device <b>11</b> includes a NAS engine, and thereby performs a file service. The NAS engine is a sort of virtual machine that is various control programs such as OS and file service programs to be executed under the control of the processor. The NAS engine of this embodiment includes a backup control function of selecting the optimal backup method for the system administrator operating the management apparatus <b>13</b> and controlling the execution thereof, and a restoration control function of controlling the restoration of the backed up data.

0061The storage subsystem <b>12</b> comprises a disk array device <b>121</b> as a physical device (PDEV), and a disk controller <b>122</b> for controlling the I/O access such as writing into and reading from the disk array device <b>121</b>.

0062The management apparatus <b>13</b> is typically a general-purpose computer, connected to the NAS device <b>11</b> and the storage subsystem <b>12</b>, and used by the system administrator to manage these components. In other words, the system administrator manages the storage system <b>10</b> by operating various management programs to be executed by the management apparatus <b>13</b>. In this embodiment, when the management apparatus <b>13</b> executes the backup manager, thereby allowing the system administrator to perform backup with the optimal backup method.

0063<figref idref="DRAWINGS">FIG. 3</figref> is a diagram explaining the configuration of the NAS device <b>11</b> according to an embodiment of the present invention. As shown in <figref idref="DRAWINGS">FIG. 3</figref>, the NAS device <b>11</b> comprises a processor <b>111</b>, a data controller <b>112</b>, a memory <b>113</b>, an I/O unit <b>114</b>, a network interface (I/F) <b>115</b>, and a channel I/F <b>116</b>.

0064The processor <b>111</b> governs the overall operation of the NAS device <b>11</b>, and executes various programs stored in the memory <b>113</b> to cause the NAS device <b>11</b> to function as a NAS engine. The processor <b>111</b> and the memory <b>113</b> are configured to exchange internal data via the data controller <b>112</b>.

0065Specifically, as described above, the basic function of the NAS device <b>11</b> is to behave as a file server, and, therefore, the processor <b>111</b> executes the file service program on a dedicated OS. Further, the NAS device <b>11</b> of this embodiment is mounted with a backup control function. Thus, the memory <b>113</b> stores a backup selection program, a file backup program, a directory configuration information acquisition program, a restoration selection program, a file restoration program, a volume restoration support program and the like, and the processor <b>111</b> executes these programs. Moreover, the memory <b>113</b> stores various types of information to be referred to by these programs; namely, backup history information <b>500</b>, directory-volume mapping information <b>600</b>, volume configuration information <b>700</b>, directory configuration information <b>800</b> and the like.

0066The I/O unit <b>114</b> is a circuit that governs the I/O control, and connects the network I/F <b>115</b> and the channel I/F <b>116</b>. The I/O unit <b>114</b> may also be connected to an extended I/F for connecting to another external board.

0067The network I/F <b>115</b> has a port not shown, and is a system circuit that functions as an interface for controlling the communication based on a file access request with the host apparatus <b>3</b> connected via the network <b>2</b>A. The network I/F <b>115</b> also has a port for connecting the management apparatus <b>113</b>, and controls the communication with the management apparatus <b>13</b>.

0068The channel I/F <b>116</b> has a port (not shown), and is a system circuit that functions as an interface for controlling the communication based on an I/O access request with the storage subsystem <b>12</b> connected via the network <b>2</b>B.

0069<figref idref="DRAWINGS">FIG. 4</figref> is a diagram explaining the configuration of the storage subsystem <b>12</b> according to an embodiment of the present invention. The storage subsystem <b>12</b> is a device for providing disk space to the host apparatus <b>3</b>, and, as described above, comprises a disk array device <b>121</b>, and a disk controller <b>122</b> for controlling the disk array device <b>121</b>.

0070The disk array device <b>121</b>, for example, is configured by including a storage medium such as hard disk drive, a disk array, a nonvolatile memory or the like. The disk array device <b>121</b> may configure a RAID (Redundant Arrays of Independence Disks). In a RAID configuration, a certain number of disk arrays configure one virtual device (VDEV), and one or more logical devices (LDEV) are defined in the virtual device. A logical device is a logical device to be recognized by the NAS engine.

0071A volume (VOL) is defined in a logical device. Here, in order to simplify the explanation, one volume is allocated to one logical device. A logical volume number is assigned to each volume. Further, a volume is partitioned into a block or a segment, which is the smallest unit of I/O access, and a logical block address is allocated to each block. Thereby, the NAS device <b>11</b> is able to access data stored in an arbitrary block of a specified volume by assigning a logical address formed from a logical volume number and a logical block address to the storage subsystem <b>12</b> based on a file access command from the host apparatus <b>3</b>.

0072The disk controller <b>122</b> comprises a channel adapter (CHA) <b>1221</b>, a cache memory (CM) <b>1222</b>, a disk adapter (DKA) <b>1223</b>, and a shared memory (SM) <b>1224</b>, and these modules or components are mutually connected via a connection <b>1225</b>. Moreover, the disk controller <b>122</b> comprises a processor <b>1227</b> and a memory <b>1228</b> connected via a bridge <b>1226</b>. The processor <b>1227</b> executes various programs stored in the memory <b>1228</b>.

0073In <figref idref="DRAWINGS">FIG. 4</figref>, although one of each of the modules is shown, by adopting a redundant configuration a plurality of modules may be used in the configuration.

0074The channel adapter <b>1221</b> has a plurality of ports (not shown), and is a system circuit that functions as a communication interface for performing communication based on an I/O access with the NAS device <b>11</b> connected to the port via the network <b>2</b>B.

0075The cache memory <b>1222</b> temporarily stores data to be exchanged between the NAS device <b>3</b> and the disk array device <b>121</b> in order to provide a high system performance to the NAS device <b>11</b>.

0076The disk adapter <b>1223</b> has a plurality of ports (not shown), and is a component or a system circuit that functions as an interface for controlling the I/O access to the disk array device <b>121</b>. Specifically, the disk adapter <b>1223</b> retrieves data from the cache memory <b>1222</b> and stores it in a prescribed storage area (block) of a volume formed in the disk array device <b>121</b> (destaging), or reads data from a prescribed storage area of the volume VOL and writes it into the cache memory <b>422</b> (staging).

0077The shared memory <b>1224</b> is a memory to be referred to by the respective modules in the storage subsystem <b>12</b>, and is configured from a RAM, a ROM, a nonvolatile RAM or the like.

0078The connection unit <b>1225</b> includes a switching device configured from a crossbar switch or the like. The connection <b>1225</b> arbitrates the competition of input data signals, switches the path of the data signals, and thereby establishes a path between the source module and the destination module.

0079The bridge <b>1226</b> is a circuit configured to connect the connection <b>1225</b> and the processor <b>1227</b>. The processor <b>1227</b> executes various programs stored in the memory <b>1228</b>, and governs operations (for instance, backup processing and the like) that are separated from the I/O service of the storage subsystem <b>12</b>. In this embodiment, the memory <b>1228</b> stores a volume backup program <b>00</b> and a volume restoration program <b>00</b>. Further, the memory <b>1228</b> may also retain a remote copy program, a snapshot program and the like.

0080<figref idref="DRAWINGS">FIG. 5</figref> is a diagram explaining the configuration of the management apparatus <b>13</b> according to an embodiment of the present invention. The management apparatus <b>13</b>, as described above, is typically a general-purpose computer, and therefore comprises hardware resources such as a CPU <b>131</b>, a memory <b>132</b>, an I/O device <b>133</b>, an I/F device <b>134</b> and the like, and software resources such as an OS, a management program and the like.

0081The CPU <b>131</b> executes the backup manager stored in the memory <b>132</b> and provides a backup tool to the system administrator. The backup manager of this embodiment communicates with the NAS device <b>11</b> and presents the optimal backup method to the system administrator. The I/O device <b>133</b>, for example, is configured from a keyboard, a pointing device, a display and the like for providing a user interface environment to the system administrator. The I/F device <b>134</b> functions as an interface for controlling the communication with an external device; in other words, the NAS device <b>11</b>. The management apparatus <b>13</b> is also connected to the storage subsystem <b>12</b> via the I/F device <b>134</b>, and is able to directly manage the storage subsystem <b>12</b>.

0082<figref idref="DRAWINGS">FIG. 6</figref> is a diagram explaining an example of the backup history information <b>600</b> according to an embodiment of the present invention. The backup history information <b>600</b> is log data accumulated each time backup processing is executed. In this embodiment, the backup history information <b>600</b> is created based on the completion result from the file backup program in the NAS device <b>11</b> or the volume backup program in the storage subsystem <b>12</b> to which backup processing was executed by the backup selection program.

0083In other words, as shown in <figref idref="DRAWINGS">FIG. 6</figref>, the backup history information <b>600</b> includes a backup date column <b>601</b>, a backup destination column <b>602</b>, a backup source column <b>603</b>, and a backup type column <b>604</b>.

0084The backup date column <b>601</b> shows the time that the backup processing was completed. The backup destination column <b>602</b> shows the location where the backup data is stored, and is formed from a network identifier (i.e., an IP address) of another device operated to store the backup data and a file name (in the case of file backup processing) or a device file name (in the case of volume backup processing) in the other device. The other device, for example, is another NAS device <b>11</b> connected via the network <b>2</b>A. Nevertheless, this does not prevent the backup data from being stored in the same NAS device <b>11</b>. In this case, the IP address may be omitted.

0085The backup source column <b>603</b> shows a directory or a file that became the backup target. Namely, the storage system <b>10</b> of this embodiment supports backup processing in directory units or file units.

0086The backup type column <b>604</b> shows the type of backup method. In this embodiment, there are a file backup method and a volume backup method. Specifically, when “File” is indicated in the backup type column <b>604</b>, this represents that file backup processing was executed, and when “Volume” is indicated in the backup type column <b>604</b>, this represents that volume backup processing was executed.

0087<figref idref="DRAWINGS">FIG. 7A</figref> and <figref idref="DRAWINGS">FIG. 7B</figref> are diagrams explaining the directory-volume correspondence relation according to an embodiment of the present invention. Specifically, <figref idref="DRAWINGS">FIG. 7A</figref> shows an example of directory-volume mapping information <b>700</b>, and <figref idref="DRAWINGS">FIG. 7B</figref> schematically shows the directory-volume correspondence relation configured according to the directory-volume mapping information <b>700</b>.

0088Specifically, as shown in <figref idref="DRAWINGS">FIG. 7A</figref>, the directory-volume mapping information <b>700</b> includes a directory column <b>701</b> and a volume column <b>702</b>, and the respective directories in the file system of the NAS device <b>11</b> are thereby associated with the volume storing such directories.

0089The directory column <b>701</b> shows the directory path of the foregoing directories. Further, the volume column <b>702</b> shows the volume name (device file name) of the volume storing the directories. In this example, the directories “/dir0/dir3/dir4” are associated with the volumes “VOL1” and “VOL2.”

0090Accordingly, the directory-volume correspondence relation according to the directory-volume mapping information <b>700</b> will be as shown in <figref idref="DRAWINGS">FIG. 7B</figref>.

0091<figref idref="DRAWINGS">FIG. 8</figref> is a diagram showing an example of the volume configuration information <b>800</b> according to an embodiment of the present invention. The volume configuration information <b>800</b> is system information concerning the configuration of the volumes created in the storage subsystem <b>12</b>. In this embodiment, at the point in time the volumes are created in the storage subsystem <b>12</b>, the dedicated OS acquires the volume configuration information <b>800</b>. The volume configuration <b>800</b> may be updated based on requests according to the acquired values configuring the volume configuration information <b>800</b>.

0092As shown in <figref idref="DRAWINGS">FIG. 8</figref>, the volume configuration information <b>800</b> includes a volume name column <b>801</b>, a total capacity column <b>802</b>, a utilization column <b>803</b>, a number of files column <b>804</b>, and a file capacity column <b>805</b>.

0093The volume name column <b>801</b> shows the name of the volumes formed in the storage subsystem <b>12</b>. In this embodiment, the volume name is synonymous with the device file name. The total capacity column <b>802</b> shows the total capacity of the disk area providing the volumes. The utilization column <b>803</b> is the ratio of usage of files in the volumes in relation to the total capacity of the volumes. The number of files column <b>804</b> shows the number of files in the volumes. The file capacity column <b>805</b> shows the size of the respective files in the volumes.

0094<figref idref="DRAWINGS">FIG. 9</figref> is a diagram explaining an example of the directory configuration information <b>900</b> according to an embodiment of the present invention. The directory configuration information is system information concerning the directory configuration of the file system formed in the NAS device <b>11</b>. In this embodiment, the directory configuration acquisition program is invoked as a result of being called from another program, refers to the volume configuration information <b>700</b>, and creates the directory configuration information <b>900</b> as illustrated in <figref idref="DRAWINGS">FIG. 9</figref>. The directory configuration information <b>900</b> may be created in advance and stored in the memory <b>1227</b>, or updated based on requests according to the acquired values configuring the directory configuration information <b>900</b>.

0095Specifically, as shown in <figref idref="DRAWINGS">FIG. 9</figref>, the directory configuration information <b>900</b> includes a directory path column <b>901</b>, a hierarchy column <b>902</b>, a number of file systems column <b>903</b>, a utilization column <b>904</b>, a lower directory status column <b>905</b>, and a number of files column <b>906</b>.

0096The directory path column <b>901</b> shows the directory path of all directories configuring the file system in the NAS device <b>11</b>.

0097The hierarchy column <b>902</b> shows the hierarchy level in the file system of the directories. For example, “1” is assigned if a certain directory is the highest-level directory in the file system to which it belongs, and “2” is assigned if it is a lower directory.

0098The number of file systems column <b>903</b> shows the number of file system configured in the volume storing the directories. In this example, the number of file systems configured in the volume storing the directories “/mnt/dir1/dir3” is shown as “2.”

0099The utilization column <b>904</b> shows the ratio of storage capacity used by the directories and its lower directory (i.e., sub directory) existing in the volume in relation to the capacity of the overall volume storing the directories. In other words, this means that the higher the utilization of a certain directory, higher the ratio of the directories in the volume.

0100The lower directory status column <b>905</b> shows whether there is a lower directory in the directories. The number of files column <b>906</b> shows the number of files existing in the directories and its lower directories in the volume storing the directories.

0101<figref idref="DRAWINGS">FIG. 10</figref> is a schematic flowchart explaining the backup processing in the storage system <b>10</b> according to an embodiment of the present invention.

0102First, the system administrator operates the management apparatus <b>13</b> to boot the backup manager, and then selects the backup processing from the menu. Thereby, the backup manager sends a directory configuration information acquisition request to the NAS device <b>11</b>. The backup manager acquires directory configuration information from the NAS device <b>11</b>, presents the initial screen of the backup wizard screen to the system administrator, and selectively receives the designation of a directory as the backup target (STEP <b>1001</b>).

0103When the backup manager receives the designation of the directory from the system administrator, it subsequently sends a backup method selection request of the directory to the NAS device <b>11</b>. The NAS device <b>11</b> receives this request and selects the optimal backup method of the designated directory (STEP <b>1002</b>).

0104Subsequently, the NAS device <b>11</b> sends the selected backup method to the management apparatus <b>13</b>. Upon receiving the selected backup method, the management apparatus presents the subsequent screen, and receives the backup processing based on the selected backup method to be executed to the directory to become the backup target (STEP <b>1003</b>).

0105When the NAS device <b>11</b> receives the execution of backup processing, it executes the backup processing to the directory to become the backup target according to the selected backup method, and acquires the backup data (STEP <b>1004</b>). When the NAS device <b>11</b> acquires the backup data, it creates and updates the backup history information <b>600</b>.

0106Instead of causing the system administrator operating the management apparatus <b>13</b> to confirm the selected backup method, the NAS device <b>11</b> may also continue to execute the backup processing after selecting the optimal backup method. In this case, preferably, the NAS device <b>11</b> sends the backup data acquisition status to the management apparatus <b>13</b>, and the management apparatus <b>13</b> presents such acquisition status.

0107Further, when the management apparatus <b>13</b> is to execute periodical automatic backup processing, the management apparatus <b>13</b> presents the selected backup method to the system administrator ex post factor as a backup report. The system administrator will be able to decide the backup schedule by referring to the backup report.

0108<figref idref="DRAWINGS">FIG. 11A</figref> and <figref idref="DRAWINGS">FIG. 11B</figref> are diagrams explaining an example of the backup wizard screen <b>1100</b> according to an embodiment of the present invention. The backup wizard screen <b>1100</b> of this embodiment includes a backup target selection screen (<figref idref="DRAWINGS">FIG. 11A</figref>) and a backup execution screen (<figref idref="DRAWINGS">FIG. 11B</figref>). The backup wizard screen <b>1100</b> is provided to the system administrator by the backup manager in the management apparatus <b>13</b>. The system administrator can command the execution of backup processing after interactively and selectively designates a directory to become the backup target according to the backup wizard screen <b>1100</b>, and confirming the selected and presented volume method.

0109Specifically, as shown in <figref idref="DRAWINGS">FIG. 11A</figref>, the backup target selection screen <b>1100</b> includes a hierarchical display <b>1101</b> of a directory structure of the file system provided by the NAS device <b>11</b>. A check box <b>1102</b> is provided to each directory, and the system administrator is able to check the directory to be backed up. In this example, the directory “/dir3/dir6” is selected as the backup target.

0110As a result of the system administrator selectively designating the directory to become the backup target and thereafter selecting the “Next” button <b>1103</b>, the backup manager sends a backup request containing the designated directory to the NAS device <b>11</b>. When the NAS device <b>11</b> receives this request, it selects the optimal backup method of the designated directory, and sends this to the management apparatus <b>13</b>.

0111The management apparatus <b>13</b> displays the backup execution screen <b>1100</b> based on the selected backup method sent from the NAS device <b>11</b>. Namely, as shown in <figref idref="DRAWINGS">FIG. 11B</figref>, the backup execution screen <b>1100</b> includes a display <b>1104</b> of the selected backup method of the designated directory. In this example, the file backup method is selected for the designated “/dir3/dir6.” The system administrator may directly receive the backup method selected by the NAS device <b>11</b>, or reselect an alternative backup method.

0112The system administrator inputs the backup destination of the directory that is a backup target into the backup destination field <b>1105</b> on the backup execution screen, and selects the “Execute” button. By way of this, the backup manager sends a backup execution request to the NAS device <b>11</b> so as to acquire the backup data under the designated condition.

0113<figref idref="DRAWINGS">FIG. 12</figref> is a diagram explaining the backup method selection processing in the NAS device <b>11</b> according to an embodiment of the present invention. The NAS device <b>11</b> performs the backup method selection processing by executing the backup selection program under the control of the processor <b>112</b>.

0114As shown in <figref idref="DRAWINGS">FIG. 12</figref>, foremost, when the NAS device <b>11</b> receives a directory configuration information acquisition request from the management apparatus <b>13</b>, it calls the directory configuration information acquisition program, and acquires the directory structure information <b>900</b> (STEP <b>1201</b>).

0115Subsequently, the NAS device <b>11</b> sends the acquired directory structure information <b>900</b> to the management apparatus <b>13</b>. The system administrator operating the management apparatus <b>13</b>, as described above, selectively designates the directory to become the backup target from the directory structure created based on the acquired directory configuration information <b>900</b>. The management apparatus <b>13</b> sends a backup method selection request of the designated directory to the NAS device <b>11</b>.

0116When the NAS device <b>11</b> receives the backup method selection request, it sets the designated directory to the current directory so as to perform the following processing based on the acquired directory structure information <b>900</b> (STEP <b>1202</b>). Namely, the current directory is a directory that is being noted by the backup selection program.

0117More specifically, the NAS device <b>11</b> determines whether the depth of the current directory in the file system to which the current directory belongs is exceeding a prescribed threshold value (STEP <b>1203</b>). In this example, the prescribed threshold value, for example, is set to “1.” To put it differently, it is determined here whether the current directory is a highest-level directory in the file system.

0118When it is determined that depth of the current directory is not exceeding the prescribed threshold value (STEP <b>1203</b>; No), the NAS device <b>11</b> subsequently determines whether the total number of file systems existing in the volume containing the file system is exceeding a prescribed threshold value (STEP <b>1204</b>). In this example, the prescribed threshold value, for example, is set to “1.” To put it differently, it is determined here whether the volume containing the file system contains a plurality of file systems.

0119When it is determined that the total number of file systems existing in the volume is not exceeding the prescribed threshold value, the NAS device <b>11</b> additionally determines whether the usage of the current directory in relation to the overall capacity of the volume falls below a prescribed threshold value (STEP <b>1205</b>). In this example, the prescribed threshold value, for example, is set to 80%. To put it differently, it is determined whether the current directory is comparatively using a lot of storage capacity in the volume.

0120When the usage of the current directory in relation to the overall capacity of the volume does not fall below a prescribed threshold value (STEP <b>1205</b>; No), the NAS device <b>11</b> selects the volume backup method regarding the current directory (STEP <b>1206</b>). The NAS device <b>11</b> thereafter notifies the backup method selected for the current directory (in other words, the volume backup method) to the management apparatus <b>13</b> (STEP <b>1210</b>). The management apparatus <b>13</b> receives this notice, and confirms with the system administrator on whether to back up the designated directory based on the volume backup method.

0121In contrast, when the determination is ‘Yes’ at any one of STEPS <b>1203</b> to <b>1205</b>, the NAS device <b>11</b> selects the file backup method regarding the current directory (STEP <b>1207</b>). The NAS device <b>11</b> further determines whether the current directory has a lower directory (STEP <b>1208</b>). When it is determine that the current directory does not have a lower directory, the NAS device <b>11</b> notifies the backup method selected for the current directory (i.e., the file backup method) to the management apparatus <b>13</b> (STEP <b>1210</b>).

0122Contrarily, when it is determined that the current directory has a lower directory, the NAS device <b>11</b> sets the lower directory to the current directory (STEP <b>1209</b>), and returns to the processing at STEP <b>1203</b>. This is in light of the fact that there are cases where the lower directory belongs to the highest-level directory of a separate file system, and such separate file system accounts for the overall volume. By way of this, it is possible to select the file backup method for the designated higher-level directory, and select the volume backup method for the lower directory. Accordingly, it is possible to select the backup method in detail according to the directory configuration information, and further improve the backup efficiency.

0123With the foregoing backup selection processing, although the backup method is selected using the combination of the three conditions illustrated in the processing of STEPS <b>1203</b> to <b>1205</b>, the present invention is not limited thereto, and the backup method may also be selected by using any one of the conditions or an arbitrary combination of two or more conditions.

0124For example, in the file system having the directory structure shown in <figref idref="DRAWINGS">FIG. 7B</figref>, let it be assumed that the system administrator just designated “dir3” as the backup target directory.

0125In such a case, the file backup method will be selected for the hierarchy level itself of the directory “dir3” (STEP <b>1203</b>; Yes). Since the directory “dir3” has a lower directory “dir4,” the optimal file backup method is determined for the directory “dir4,” and the volume backup method is selected thereby. In other words, directory “dir4” or lower will be subject to the volume backup processing to the volumes VOL<b>1</b> and VOL<b>2</b> forming the file system B.

0126<figref idref="DRAWINGS">FIG. 13</figref> is a schematic flowchart explaining the restoration processing in the storage system <b>10</b> according to an embodiment of the present invention.

0127First, the system administrator operates the management apparatus <b>13</b> to boot the backup manager, and then selects the restoration processing from the menu. The backup manager presents the initial screen of the restoration wizard screen <b>1400</b> described later to the system administrator, and receives the designation of the directory to become the restoration target (STEP <b>1301</b>). The backup manager acquires the backup history <b>600</b> and the directory configuration information <b>900</b> from the NAS device <b>11</b> for creating this kind of restoration wizard screen <b>1400</b>.

0128When the backup manager receives the designation of the directory to become the restoration target from the system administrator, it sends a backup data candidate request of that directory to the NAS device <b>11</b>. Upon receiving this request, the NAS device <b>11</b> refers to the backup history <b>600</b>, creates list of the backup data acquired from the backup processing performed to the designated directory, and sends this list to the management apparatus <b>13</b> (STEP <b>1302</b>). Namely, when the directory is periodically backed up, since a plurality of backup data will exist in the directory, the NAS device <b>11</b> creates a list of such backup data and presents this list to the system administrator (STEP <b>1303</b>).

0129The system administrator selects one backup data to be restored from the presented backup data candidate list (STEP <b>1304</b>). The management apparatus <b>13</b> sends a restoration execution request based on the selected backup data to the NAS device <b>11</b>.

0130When the NAS device receives the restoration execution request, it executes restoration processing based on the backup data according to the restoration execution request (STEP <b>1305</b>).

0131Incidentally, when the backup data according to the restoration execution request is based on the volume backup method, the volume restoration support processing described later will be performed.

0132<figref idref="DRAWINGS">FIG. 14A</figref> and <figref idref="DRAWINGS">FIG. 14B</figref> are diagrams explaining an example of the restoration wizard screen <b>1400</b> according to an embodiment of the present invention. The backup wizard screen <b>1400</b> of this embodiment includes a restoration target selection screen (<figref idref="DRAWINGS">FIG. 14A</figref>) and a restoration execution screen (<figref idref="DRAWINGS">FIG. 14B</figref>). The restoration wizard screen <b>1400</b> is presented to the system administrator by the backup manager in the management apparatus <b>13</b>. The system administrator can command the execution of restoration after interactively selecting the directory to be restored using the restoration wizard screen <b>1400</b> and confirming the backup data of the directory.

0133Specifically, as shown in <figref idref="DRAWINGS">FIG. 14A</figref>, the restoration target selection screen includes a hierarchical display <b>1401</b> of a directory structure of the file system provided by the NAS device <b>11</b>. A check box <b>1402</b> is provided to each directory, and the system administrator is able to check the directory to be restored. In this example, “/dir3/dir6” is selected as the backup target. Further, a directory without any backup data and which cannot be restored, as shown with reference numeral <b>1403</b>, is displayed inactively. In this example, “dir2” is displayed inactively, and cannot be selected.

0134As a result of the system administrator designating the directory to become the restoration target and thereafter selecting the “Next” button <b>1404</b>, the backup manager sends a backup request candidate request containing the designated directory to the NAS device <b>11</b>. When the NAS device <b>11</b> receives this request, it extracts the candidate of backup data of the designated directory, and sends this to the management apparatus <b>13</b>. Backup data, for instance, is extracted for each date backup was executed to the directory.

0135The management apparatus <b>13</b> displays a restoration execution screen based on the candidate of the extracted backup data sent from the NAS device <b>11</b>. In other words, in <figref idref="DRAWINGS">FIG. 14B</figref>, the restoration execution screen includes a display <b>1405</b> of the backup data candidate list of the designated directory. The system administrator selects one backup data of a certain point in time to be restored in the restoration execution screen. In this example, restoration of backup data at “2007/05/1200:00:00” is selected regarding the designated “/dir3/dir6.” In this case, the backup manager may also select the backup data acquired by the most recent backup processing as a default.

0136The system administrator selects and confirms backup data regarding the directory that is the restoration target, and selects the “Execute” button <b>1406</b> in the restoration execution screen. Thereby, the backup manager sends a restoration execution request to the NAS device <b>11</b> so as to perform restoration based on the selected backup data.

0137<figref idref="DRAWINGS">FIG. 15</figref> is a flowchart explaining the restoration data selection processing in the management apparatus <b>13</b> according to an embodiment of the present invention.

0138First, the system administrator operates the management apparatus <b>13</b> to boot the backup manager, and then selects restoration processing. The management apparatus <b>13</b> executes a restoration selection program, requests the backup history information <b>600</b> and the directory configuration information <b>900</b> to the NAS device <b>11</b>, and acquires such information from the NAS device <b>11</b> (STEP <b>1501</b>).

0139Subsequently, the management apparatus <b>13</b> presents the directory structure hierarchically based on the acquired backup history information <b>600</b> and the directory configuration information <b>900</b>, and receives the designation of the directory to become the restoration target from the system administrator (STEP <b>1502</b>). Here, a directory without any backup history is displayed inactively so that it cannot be selected by the system administrator.

0140When the management apparatus <b>13</b> receives the designation of the directory to become the restoration target (STEP <b>1503</b>), it refers to the backup history information <b>600</b>, and extracts the candidate of backup data executed to the designated directory (STEP <b>1504</b>). The management apparatus <b>13</b> thereafter presents a list of the extracted backup data (STEP <b>1505</b>). The system administrator selects one backup data at the point in time it is to be restored from the presented backup data candidate.

0141When the management apparatus <b>13</b> receives the selection of backup data (STEP <b>1506</b>), it sends the restoration execution request based on the selected backup data to the NAS device <b>11</b> (STEP <b>1507</b>). Upon receiving this request, the NAS device <b>11</b> executes restoration processing and acquires the backup data.

0142<figref idref="DRAWINGS">FIG. 16</figref> is a flowchart explaining the restoration processing in the NAS device <b>11</b> according to an embodiment of the present invention.

0143As shown in <figref idref="DRAWINGS">FIG. 16</figref>, when the NAS device <b>11</b> receives the restoration execution request based on the backup data selected regarding the directory to become the restoration target designated by the system administrator (STEP <b>1601</b>), it sets the designated directory to the current directory (STEP <b>1602</b>). Namely, the current directory is a directory that is being noted by the restoration processing program.

0144The NAS device <b>11</b> thereafter refers to the backup history information <b>600</b>, and determines whether the selected backup data is backup data acquired by executing the volume backup processing (STEP <b>1603</b>). When the selected backup data is backup data acquired by executing the volume backup processing (STEP <b>1603</b>; Yes), as described above, the NAS device <b>11</b> calls the volume restoration support processing program and executes the requested restoration processing.

0145Contrarily, when the selected volume backup processing is backup data acquired by executing the volume backup processing (STEP <b>1603</b>; No), the NAS device <b>11</b> executes file restoration processing to the current directory based on the selected backup data (STEP <b>1604</b>).

0146When the NAS device <b>11</b> completes the file restoration processing to the current directory, it determines whether the current directory has a lower directory (STEP <b>1605</b>). When the current directory does not have a lower directory (STEP <b>1605</b>; No), the NAS device <b>11</b> ends the restoration processing. Contrarily, when the current directory has a lower directory (STEP <b>1605</b>; Yes), the NAS device <b>11</b> sets the lower directory to the new current directory (STEP <b>1606</b>), returns to the processing at STEP <b>1603</b>, and similarly executes restoration processing regarding the new current directory.

0147<figref idref="DRAWINGS">FIG. 17</figref> is a flowchart explaining the restoration processing in the NAS device <b>11</b> according to an embodiment of the present invention, and more specifically is a flowchart explaining the volume restoration support processing.

0148Specifically, when it is determined that the backup data acquired at STEP <b>1603</b> of <figref idref="DRAWINGS">FIG. 16</figref> is backup data acquired by executing the volume backup processing (STEP <b>1603</b>; Yes), the NAS device <b>11</b> specifies the logical device including the volume storing the backup data acquired based on the volume backup processing being performed to the directory as the restoration target (STEP <b>1701</b>). Here, let it be assumed that one volume corresponds to one logical device.

0149Subsequently, the NAS device <b>11</b> mounts the specified logical device on a temporary directory “rst_tmp” for restoration (STEP <b>1702</b>). The NAS device <b>11</b> thereafter performs file restoration processing to the directory as the restoration target under the mounted temporary directory “rst_tmp” (STEP <b>1703</b>).

0150When the NAS device <b>11</b> ends the file restoration processing regarding the target directory, it performs unmounting in order to separate the logical device from the file system (STEP <b>1704</b>).

0151Thereby, even when the file backup processing is executed regarding a specified directory in the individual file systems, the NAS device <b>11</b> is able to reliably perform restoration.

0152For example, in a file system having the directory structure shown in <figref idref="DRAWINGS">FIG. 7B</figref>, assumed that the backup processing was performed to the directory “dir4” and backup data was acquired. Further, assumed that the system administrator designated the directory “dir7” as the restoration target.

0153In this case, as shown in <figref idref="DRAWINGS">FIG. 18</figref>, the directory “dir4” has been subject to volume backup processing. Accordingly, in order to restore the directory “dir7,” the volumes VOL<b>3</b> and VOL<b>4</b> as the backup data acquired based on volume backup processing are specified, and the file system B_Backed up formed from the foregoing volumes is temporarily mounted. Then, restoration processing is performed by copying the contents of the directory “dir7” in the file system B_Backed up to the file system B.

0154In the foregoing example, although a case was explained of restoring a specified directory subject to volume backup, when restoring the overall volume that was subject to a volume backup, the system administrator may command the execution of the volume restoration processing to the storage subsystem <b>12</b> via the backup manager.

0155A modified example of this embodiment is now explained. With the modified example of this embodiment, the management apparatus <b>13</b> is mounted with the backup selection function instead of the NAS device <b>11</b>. The management apparatus <b>13</b> is also mounted with the file backup/restoration function. <figref idref="DRAWINGS">FIG. 19</figref> is a diagram explaining a modified example of the storage system according to an embodiment of the present invention.

0156As shown in <figref idref="DRAWINGS">FIG. 19</figref>, the management apparatus <b>13</b> further includes, in addition to the backup manager, a backup/restoration selection program, a file backup/restoration program, and a volume support program. Further, the NAS device <b>11</b> includes a directory configuration information acquisition program, and sends the directory configuration information <b>900</b> to the management apparatus <b>13</b> according to a request from the backup selection program.

0157The backup selection program of the management apparatus <b>13</b> selects the optimal backup method based on the sent directory configuration information <b>900</b>, and presents this to the user. When the management apparatus <b>13</b> selects the file backup method, it boots the file backup program and executes file backup processing. Further, when the management apparatus <b>13</b> selects the volume backup method, it commands the storage subsystem <b>12</b> to execute volume backup.

0158The hardware configuration and the processing contents of the respective programs of the storage system <b>10</b> are the same as the foregoing embodiment, and the explanation thereof is omitted.

0159Another embodiment of the present invention is now explained. <figref idref="DRAWINGS">FIG. 20</figref> is a diagram showing the configuration of a computer system according to another embodiment of the present invention. In this embodiment, a storage system utilizing GNS (Global Name Space) technology is configured.

0160Specifically, as shown in <figref idref="DRAWINGS">FIG. 20</figref>, the computer system <b>1</b> of this embodiment further includes a GNS server <b>14</b> connected to the network <b>2</b>A. The NAS device <b>11</b>, the storage subsystem <b>12</b>, and the GNS server <b>14</b> are connected to the management apparatus <b>13</b> via the network <b>2</b>A.

0161GNS is technology of transparently changing the arrangement of the shared directory between the file servers (in other words, the NAS devices <b>11</b>) connected to a single network from a client computer (in other words, the host apparatus <b>3</b>). As a result of using this kind of GNS technology, it is possible to change the arrangement of the directory and balance the load according to the access load in the file server, and the cost performance of the overall storage system can be improved thereby.

0162More specifically, with GNS, the logical address of the shared directory designated by the client computer is converted into a physical address of the file server in which the directory is actually arranged. Thereby, even if the physical location of the shared directory is changed, the client computer is able to access the shared directory using the same logical address.

0163Referring to <figref idref="DRAWINGS">FIG. 20</figref>, the GNS server <b>14</b> is a server computer that performs address conversion of directories provided by the individual NAS devices <b>11</b> connected to the same network <b>2</b>A. In other words, the GNS server <b>14</b> is uniformly managing the logical/physical address of the NAS device <b>11</b> on the network <b>2</b>. Accordingly, the host apparatus <b>3</b> of this embodiment does not directly access the directories provided by the NAS device <b>11</b>, but rather once requests the GNS server <b>14</b> the conversion of the logical address of the directory, and accesses the NAS device <b>11</b> according to the physical address replied from the GNS server <b>14</b>. The GNS server <b>14</b> realizes the foregoing function by executing the GNS service program under the control of the CPU not shown.

0164The GNS server <b>14</b> of this embodiment is also mounted with the foregoing backup selection program, restoration selection program, and volume restoration support program. The GNS server <b>14</b> executes the backup selection program based on the command from the backup manager of the management apparatus <b>13</b>. The GNS server <b>14</b> acquires the directory configuration information from a specified NAS device <b>11</b> including the directory as the backup target, selects the optimal backup method based on the directory configuration information, and sends this to the management apparatus <b>13</b>. Upon receiving this method, the management apparatus <b>13</b> presents the selected backup method to the system administrator. The GNS server <b>14</b> requests the NAS device to execute file backup, or requests the storage subsystem to execute volume backup according to the selected backup method.

0165Thereby, even with a storage system comprising the GNS server <b>14</b>, the optimal backup method of the directory as the backup target is selected based on the directory configuration information and presented to the system administrator. Accordingly, the system administrator is able to confirm the presented backup method, and more easily manage the system.

0166Each of the foregoing embodiments is exemplifications for explaining the present invention, and are not intended to limit the scope of the present invention. The present invention may be implemented in various modes so as long as it does not deviate from the gist of this invention.

0167For instance, as evident from each of the foregoing embodiments, the respective programs that realize the backup/restoration mechanism of the present invention may be mounted on an arbitrary device so as long as the functions of these programs do not depend upon a unique device. Accordingly, for example, in the foregoing embodiment comprising the GNS server <b>14</b>, although the GNS server <b>14</b> is mounted with the backup selection program, such backup selection program may also be mounted on the management apparatus <b>13</b>.

0168The present invention may be broadly applied to storage systems using NAS.