Data transfer interface

The present invention relates to an interface and a method for interconnecting data storage drives and a control device. In particular, the present invention relates to a data transfer interface for transferring data from/to interconnected data storage drives.

Data interfaces allow a host device, like a computer system, to send and receive information for data storage devices such as hard disk drives or optical data storage media. For connecting such peripheral devices to the host, the ATA (AT-Attachment) bus of the original IBM/AT PC is still widely in use. The ATA bus standard has been extended with the AT Attachment Packet Interface (ATAPI) and is since then named ATA/ATAPI. The ATA/ATAPI is an interface extension that supports connection of external devices to computer systems, in particular, to personal computers.

The ATA/ATAPI standard defines a set of registers used by the peripheral devices and host computer to effect the transfer of data. This set of registers is named task file. Peripheral devices require device-specific control information such as a sector, a cylinder number or a head ID to search for position information of a read/write head. This information is individually transferred and written into a register of the peripheral device.

US-B1-6 301 625 discloses a PC-based disk array system which comprises an array controller which controls an array of ATA disk drives. The array controller and the disk drive controllers are jointly connected to a packet switch bus.

A communication session with a peripheral device using ATA/ATAPI proceeds through several phases. The host computer writes a command to a command register on the ATA/ATAPI peripheral during a command phase. Thereafter, a data phase is entered in which the data is transferred from/to the peripheral device.

US-A-6 119 183 describes a switching system simulating two SCSI ports for connecting a SCSI device having only one port. It is suggested to enhance the transmission reliability by using a differential SCSI interface, comprising a pair of wires having complementary polarities.

When copying data between two peripheral devices connected to a host, the data is first read from one of the peripheral devices, transferred to the host and, finally, transferred and written to the second peripheral device. Such a processing is time consuming, in particular when copying large amounts of data.

In view of this prior art drawback, it is desirable to provide a data transfer interface and a method for transferring data between data storage drives enabling a more efficient use thereof.

This is achieved by the features of the independent claims.

According to a first aspect of the present invention, a data transfer interface for interconnecting two data storage drives and a control device is provided. The data transfer interface comprises a plurality of data lines jointly connecting both data storage drives and the control device. The data transfer interface further comprising a plurality of control data lines jointly connecting both data storage drives and the control device. Further, data transfer interface comprises a first read/write command line connecting one of the data storage drives and the control device. In addition, the data transfer interface comprises a second read/write command line connecting the other of the data storage drives to the control device.

According to another aspect of the present invention, a computer system is provided having a connector connectable to data storage drives. The connector comprises a plurality of data lines, a plurality of control data lines and a first read/write command line. Said first read/write command line being connectable to one of said data storage. drives. In addition, a second read/write command line is provided being connectable to a second one of said data storage drives.

According to a further aspect of the present invention, a method for connecting two data storage drives and a control device is provided. The control device initialises both connected data storage drives for preparing a data read and/or write procedure by sequentially selecting one of both connected data storage drives and assigning respective data storage areas thereon. Data are transferred to/from said data storage drives in accordance with the assigned data storage areas by concurrently instructing both data storage drives by individual read/write commands.

It is the particular approach of the present invention to enable an individual control of two data storage drives which are jointly connected to a control device. While data lines and control lines are jointly connected to the two data storage drives, separate read/write lines enable an individual control of both connected data storage drives.

By duplicating the read/write lines, each of the data storage drives can be accessed individually. In this manner, both connected data storage drives may be configured to directly transfer data in-between. This is accomplished by instructing one data storage drive to read data and the other data storage drive to write data while the data is directly transferred without any intermediate data buffering in the control device or host. Consequently, a data copy procedure can be accelerated considerably.

The provision of an additional read/write line enables an individual initialisation of both drives, meaning that data storage areas on both drives are individually selectable. Thus, in an alternative application the data transfer interface of the present invention enables a copy of data from a control device simultaneously to two different data storage drives.

Preferably, the data transfer is controlled by the control device such that data signals and control signals are jointly output to both connected data storage drives while read/write signals are individually output to each of the connected drives. In this manner, only a minimum adaptation effort is required in order to use a single set of data lines and control lines to independently control the operation of separate data storage drives.

Preferably, each read/write line comprises separate lines for transferring a read command and for transferring a write command.

Preferably, the data lines, the control lines and the first read/write command lines are configured in accordance with the ATA/ATAPI standard. By the provision of one additional read/write command line, the connected drives can be controlled individually such that an accelerated data copying can be achieved.

Preferably, one of the drives is an optical disk drive and the other drive is a hard disk drive. For such a data storage drive configuration, data from the optical disk drive can be transferred in a simple and fast manner to the hard disk drive.

The present invention enables a transfer of a large amount of data within a short period of time. In this manner, software updates, operation data like navigation data, multimedia data like video and audio, and other data can be transferred from an optical storage medium for later use to a re-writable storage medium like a hard disk drive. When the data from the hard disk drive is employed during operation, for instance for navigation purposes, the optical disk drive can be used at the same time for a reading/writing of other data.

Preferably, the data storage drives are controlled by setting registers provided in each of the data storage drives, respectively.

Further preferred embodiments of the present invention are the subject matter of dependent claims.

Additional features and advantages of the present invention will become apparent from the following description of the invention as illustrated in the drawings, wherein: <dl id="dl0001"><dt>Fig. 1</dt><dd>schematically illustrates a prior art single channel data interface jointly connecting two data storage drives to a host device;</dd><dt>Fig. 2</dt><dd>schematically illustrates a double channel prior art data interface for individually connecting two data storage drives to a host device;</dd><dt>Fig. 3</dt><dd>schematically illustrates a data transfer interface in accordance with the present invention;</dd><dt>Fig. 4</dt><dd>illustrates in a block diagram form the configuration of task file registers provided in the data storage drives connected to the data transfer interface in accordance with the present invention;</dd><dt>Fig. 5</dt><dd>schematically illustrates the register configuration in accordance with the single channel data interface approach;</dd><dt>Fig. 6</dt><dd>schematically illustrates the register configuration of a data transfer interface in accordance with the present invention; and</dd><dt>Fig. 7</dt><dd>is a flow chart illustrating the steps performed in accordance with the present invention for concurrently transferring data from/to the data storage drives.</dd></dl>

The illustrated embodiments of the present invention will now be described with reference to the drawings.

Referring to Fig. 1, a prior art single channel data transfer interface is illustrated connecting two data storage drives 110, 120. Each of the data storage drives 110, 120 is provided with a respective data connector 115, 125. Both data storage drives 110 and 120 share a single host interface 135 provided at a host or control device 130. A plurality of data lines 140, a plurality of control lines 150 and a read/write line 160 are jointly connected to both data storage drives 110, 120. By selecting a particular identifier bit in a drive/head register provided in each of the data storage drives 110, 120, one of the data storage drives 110, 120 is selected for carrying out a read or write operation.

In accordance therewith, only a single one of both data storage drives can be selected at a time and perform a read or write operation. For copying data between both data storage drives, the data needs to be read and transferred from a first one of the data storage drives 110 to the host 130, to be buffered therein and to be subsequently transferred from the host 130 to the second data storage drive 120. The total transfer time for copying data between both data storage drives 110, 120 is represented by the accumulated time period for reading and transferring data from the first data storage drive to the host, for buffering the read data in the host and for transferring and writing data from the host onto the second data storage drive.

Referring to Fig. 2, the double channel data transfer interface approach is illustrated. Both data storage drives 210, 220 are connected to the host 230 by individual data transfer interfaces. For each of the data transfer interfaces, respective data connectors 215, 233 and 225, 237 are provided to link the data storage drives to the host and to enable an individual operation of both data storage drives 210, 220. The host can prepare a data transfer between both data storage drives 210, 220 by individually initialising both data storage drives and transferring the data in-between through the host.

While the prior approach illustrated in Fig. 1 results in a prolonged data transfer time for copying data between both data storage drives, the approach illustrated in Fig. 2 requires an increased hardware effort.

The present invention aims to reduce the data processing time required in accordance with the approach of Fig. 1 and to reduce the hardware effort as required by the approach shown in Fig. 2.

Fig. 3 illustrates a data transfer interface configured in accordance with the present invention. Both data storage drives 310, 320 are equipped with respective data connectors 315, 325 for establishing connection to a host 330 by connector 335. The data lines 340 and the control lines 350 of both data storage drives 310, 320 are jointly connected to the host 330. In contrast to the prior art approach as described, for instance, in connection with Fig. 1, read/write lines 360, 370 are individually provided for each of the data storage drives 310, 320. In accordance therewith, the host 330 is additionally equipped with a connector 375 for the supplementary read/write line 370.

The provision of individual read/write lines 360, 370 enables a particular selection of one of the data storage drives 310, 320 for operation. In this manner, both data storage drives can be initialised separately, in particular different data storage areas can be defined and different read/write commands outputted to instruct the operation of both data storage drives. Consequently, a direct data transfer can be accomplished such that one of the drives is reading data from a predefined data storage portion while the second drive is writing the received data to a designated storage portion.

In this manner, huge amounts of data can be transferred in a short period of time from a first storage drive, e.g. a DVD drive, to a second data storage drive, for instance a hard disk drive.

Such data transfer interfaces can be advantageously used in vehicle entertainment and information systems. Such systems require, for instance, a repetitive update of navigation information. When a vehicle entertainment and information system only comprises a single DVD drive, a time consuming update procedure blocks the use of the DVD drive for other applications, such as a DVD or CD reproduction operation of audio and/or video data. By employing a data transfer interface in accordance with the present invention, the update information can be transferred efficiently and the time needed is reduced considerably.

In accordance with the ATA/ATAPI standard, each data storage drive comprises a set of registers named AT task file representing a communication interface between the host device and a data storage drive for transferring control data and instructing the operation of the data storage drive. The control of the connected data storage drive by means of task file registers is described in more detail in connection with figures 4 to 7.

The host or control device sends instructions to a task file 410, 420 provided in each of the data storage drives 310, 320. Each task file comprises a data register 412, 422, a position register 414, 424 and a command register 416, 426. Other registers may also be provided.

The task file 410, 420 of both data storage drives 310, 320 are jointly connected to control lines (as register address lines) on the one hand and to data lines on the other hand. While the control lines select a particular register from all registers provided within the task file 410, 420, the data lines provide the data to be written into the selected register.

For data transfers, a data storage area to be used for a data read or write operation is first selected. For this purpose, a position information is transferred to the position register 414, 424 for positioning of the read/write head in order to command the data storage drive's servomotor to move the head to the desired position.

Next, the desired read or write operation to be performed by the data storage drive during the data transfer is written into the respective command registers 416, 426 in accordance with data transferred on the control lines and data lines.

During a data read or write operation from/onto the data storage medium, the outputted or received data are written into the respective data register 412, 422 of the data storage drives 310, 320.

In order to be able to individually initialise each task file 410, 420 of both connected data storage drives, the read/write lines are provided separately for each of the drives. Only the provision of individual read/write lines enables a transfer of control data for selecting a particular register and data to be written therein for a single one of the two data storage drives. That data storage drive will write the initialisation data provided on the data and control lines into its task file register which has a write command applied on its read/write line.

Preferably, the read/write lines interconnecting the host and the data storage drive consists of two lines, including one line for providing a read command and another line for providing a write command.

In this manner, the data transfer interface enables a direct data transfer from the data register 412 of one of the data storage drives 410 to the data register 422 of the other data storage drive 420, i.e. the target data storage drive. The data transfer interface of the present invention avoids any further data transfer or buffering operations.

Both data storage drives share control (address) lines and data lines from the host interface. The data lines at the host interface may be switched to high impedance. As only one additional read line (DIOR) and write line (DIOWR) needs to be added, the data transfer interface only requires a small amount of additional hardware. For a copy of data between both interconnected data storage drives, both drives are first initialised sequentially while the reading of the data register of the source data storage drive is effected at the same time of writing new data into the data register of the target data storage drive. A buffering of data is not required.

While conventionally the data are transferred through the host between both data storage drives, the present invention enables a direct data transfer between the interconnected data storage drives. Thus, the processing power of the host is released for other operations during the direct data transfer phase as only a reduced hardware effort and processing load is required during this stage.

In addition to a direct data transfer between both interconnected data storage drives, both drives may be operated to simultaneously store identical data thereon. This is advantageously employed for back-up procedures or a computer RAID procedure. The term RAID is designating a Redundant Array of Inexpensive Disks. A RAID includes a number of data storage drives which act as an extremely reliable single disk drive. By employing the data transfer interface of the present invention, the data to be stored can be duplicated in a simple manner.

The data transfer interface can be connected to all peripheral devices equipped with a standardized connector. In particular, the data storage drives of the present invention can be optical disk drives, hard disk drives, floppy disk drives, flash memories and silicon drives. The types of peripheral devices connectable to the data transfer interface of the present invention is not limited to the explicitly mentioned data storage means. There exists a plurality of other kinds of peripheral devices connectable thereto.

Fig. 5 and Fig. 6 illustrate the task file registers of the data storage drives together with the connected data lines in more detail. While Fig. 5 illustrates the configuration in accordance with the prior art single channel approach (cf. Fig 1), Fig. 6 represents a configuration in accordance with the present invention.

Both data storage drives are denoted by reference numerals 510, 520. Each drive has a read/write head 515, 525 for reading and writing data from/on a data storage medium incorporated therein. Respective task file registers 530, 540 are provided in each of the storage drives. Each task file register 530, 540 comprises a plurality of registers 550 as previously described in connection with Fig. 4.

Both task file registers 530, 540 share common data lines 560 and control lines 570. While the task file registers shown in Fig. 5 also share a common read/write line 580, the task file registers shown in Fig 6 are provided with individual read/write lines 610, 620. The provision of individual read/write lines ensures that both task file registers 530, 540 can be controlled individually and each of the data storage drives can be initialised irrespective of the status of the other data storage drive.

When directly copying data between a data sector of a first data storage drive to a data sector of the second data storage drive, the following steps are performed. First, it is checked whether or not the first data storage drive is an inoperative state. Next, the initialisation parameters are written into the task file register of the first data storage drive, in particular the head position is written into the "HEADPOS" register and the "COMMAND" register is set to a read operation.

After the initialisation procedure 710 for the first data storage drive is completed, the same procedure is performed for the second data storage drive, meaning that the data storage area is defined in the "HEADPOS" register while a write command is set in the "COMMAND" register (step 720).

After both initialisation procedures 710, 720 for the data storage drives are completed, the first data storage drive is instructed to read data while the second data storage drive is instructed to write data (step 730).

When the first data storage drive provides read data and the second data storage drive requests for data to be written (these states are preferable indicated by the "STATUS" registers shown in Fig. 6), the data lines are separated from the host and a direct data transfer for simultaneously performing a read access to the data register of data storage drive 1 and a write access to the data register of data storage drive 2 is carried out.

According to a preferred embodiment, data lines 340 may be disconnected from the host 330 in Fig. 3 when directly transferring data between both data storage devices 310, 320 is accomplished by the additional provision of a switch means 390. According to a particular implementation, the switch means 390 is a tri-state driver. Tri-state driver 390 connects/disconnects the host branch of the data lines 340 to/from the host 330.

In contrast thereto, the prior art approach as shown in Fig. 5 is controlled such that all data storage drives connected to the host are always set in accordance with the initialisation data. A drive selection is only effected during transmission of the read or write operation command which is accompanied by an identifier. The identifier being an identification bit is denoted by reference numerals 415, 425 in Fig. 4. Only when the transmitted identifier matches a previously stored identification value in the respective drive, the drive will perform the operation as instructed by the initialisation data. Thus, the prior art interface does not allow to operate both drives at the same time.

In accordance with the ATA/ATAPI standard, the data lines 340 comprise 16 individual lines in parallel, while the data control lines 350 are composed of 3 address lines. Further, there are two additional lines CS0 and CS1 which also serve for addressing purposes in the data transfer interface. The read/write command line 360 is composed of two individual lines, a first one for the transmission of a read command and a second one for the transmission of a write command. The additional read/write line 370 is configured accordingly. Thus, the data transfer interface of the present invention can be connected to all peripheral devices having a standardized data connector.

Although the previous description only relates to a connection of two data storage drives to a host device, the present invention is not limited thereto. As it is obvious for a skilled person, additional data storage drives can be connected in an identical manner, i.e. by providing additional read/write lines for individually controlling an initialisation procedure thereof. The data transfer interface of the present invention can thus copy data between any subset of two data storage drives from all of the interconnected data storage drives.

In summary, the present invention provides a data transfer interface which individually sets the control parameters for both data storage drives. In this manner, a direct data transfer between both data storage drives can be accomplished and accelerated copy of data achieved.