Method and system for local clock backup

0001The invention relates to a method and a system for backing up the local clock of an IT perimeter, configured on a multicell platform of IT resources.

0002For a multiprocessor system, the document <patcit id="pcit0001" dnum="FR2767935A"><text>FR 2 767 935 A</text></patcit> discloses the manner of synchronizing different modules with respect to an evolving date over time, using one of the processors as master processor.

0003At the present time, one of the axes of evolution of hardware and / or computer systems relates to the implementation of maximum flexibility of configurable computer resources, for the benefit of a user, locally having significantly reduced computer resources. .

0004In current configurable or reconfigurable computer systems, as shown in <figref idref="f0001">figure 1a</figref>, a multicellular platform PF of IT resources is used, which can be configured from an administration tool MT, by a user, according to a perimeter Pi computer formed by a given number of cells, each cell C_{K J} comprising at least one central processing unit, working memories, and a local hardware component capable of delivering a local clock signal. Each IT perimeter is managed by a specific multiprocessor operating system and can, therefore, be configured by the user for the execution of an operating activity. In general, an operating activity corresponds to an application requiring specific computing power depending on the type and volume of data processed by this application.

0005More particularly, it is recalled that the administration tool can advantageously be constituted by a microcomputer connected in a local network, extended to the multicellular platform.

0006Finally, common resources, such as peripheral elements, mass memory, of the system disk type, can be associated with the cellular platform.

0007Such systems correspond to systems or machines, usually designated partition machines, and normally allow the installation and execution of different operating activities in the different partitions of the platform. However, when such an installation is carried out, it is generally not possible to transfer an installation to another partition without reinstallation or physical manipulation while also retaining the context of execution of the abovementioned operating activity.

0008With regard to existing mechanisms, allowing the dynamic resumption of operating activities of a computer system by another computer system, provided with the same operating system, such mechanisms essentially use two systems which must imperatively synchronize their execution context and which only share their data disks and not their system disk.

0009Finally, the static mechanisms for resuming operating activity require either the reinstallation of an equivalent system, or, if necessary, the physical transfer of system disk to an equivalent system, or even rewiring of access to the system disk. replaced to an equivalent replacement system.

0010The object of the present invention is to remedy all of the aforementioned drawbacks of the solutions proposed by the known prior art.

0011In general, an object of the present invention is the implementation of a fully flexible partition machine, by means of which an operating activity, installed and executed on a partition constituting a common computer perimeter configured on a platform - multicellular form, can be recharged and restarted in another IT perimeter, while preserving the essential environmental parameters of this operating activity, in the absence of any physical intervention.

0012In particular, an object of the present invention is the implementation of the reloading and restarting process of any operating activity from one IT perimeter to another IT perimeter of a multicellular platform, independently and transparently vis-à-vis the operating system selected.

0013More specifically, an object of the present invention is the implementation of a method and a system for backing up the local clock of a computer perimeter configured as a partition of a multicellular platform of computer resources , in order to allow the conservation of the essential environmental parameters of any operating activity executed on this IT perimeter, then on any separate IT perimeter configured on this multicellular platform.

0014The method for backing up the local clock of an IT perimeter configured on a multi-cellular IT resource platform within the framework of an operating activity applies to a platform in which each IT perimeter is managed by a specific operating system that can be configured by a user from an administration tool, for the execution of the operating activity on at least one current perimeter or on successive separate IT perimeters.

0015It is remarkable in that it consists in establishing, for the assembly constituted by the administration tool and by all the computer perimeters configurable on this multicellular platform, an absolute reference clock.

0016For each current IT perimeter configured at the request of a user, to which is associated a current local clock allowing to manage an operating activity from the operating system, it also consists of calculating and memorizing, for each activity of 'running operation on this current IT perimeter of the multicellular platform, a backup attribute containing, in addition to the time management parameters of this operating activity, with reference to the current local clock, a time shift parameter of the time management parameters with respect to the absolute reference clock .

0017When reloading the operating activity for continuation of execution on a following IT perimeter, distinct from the current IT perimeter and with which is associated a next local clock, distinct from the current local clock associated with the current IT perimeter, it consists in recalculating the time management parameters of the operating activity from the time offset parameter of the time management parameters vis-à-vis the absolute reference clock and updating the 'Next distinct local clock associated with this following distinct IT perimeter, prior to the launch of said operating activity for further execution.

0018The process which is the subject of the present invention finds application in networked computing, and, in particular, in the implementation of computer servers supporting partitions that can be used simultaneously and successively by different operations or activities of operations, as well as the implementation of very flexible computer servers and availability of use between computer servers, allowing to transfer without difficulty or complex operation an operating activity from a computer server to another computer server.

0019It will be better understood on reading the description and on observing the drawings below, in which, in addition to the <figref idref="f0001">figure 1a</figref> and the <figref idref="f0001">figure 1b</figref> illustrative of a partitionable machine on a computer platform of the prior art,<ul id="ul0001" list-style="dash" compact="compact"><li>the <figref idref="f0002">figure 2a</figref> represents, by way of illustration, a general flowchart for implementing the method which is the subject of the present invention,</li><li>the <figref idref="f0002">figure 2b</figref> represents, by way of illustration, a specific implementation detail without limitation of one of the steps of implementation of the method which is the subject of the invention represented in <figref idref="f0002">figure 2a</figref>,</li><li>the <figref idref="f0003">figure 2c</figref> represents, by way of illustration, a specific process for implementing the method which is the subject of the invention, during a voluntary modification of the date and / or time parameters by the user,</li><li>the <figref idref="f0003 f0004 f0005">figures 3a to 3e</figref> represent, by way of illustration, specific modes of implementation of the steps of the process which is the subject of the invention, as shown in <figref idref="f0002">figure 2a</figref>, during the introduction of modifications of a current IT perimeter into a separate IT perimeter by a user, during an operation to execute an operating activity by the latter,</li><li>the <figref idref="f0005">figure 4</figref> represents a system for backing up the local clock of a computer perimeter, in accordance with the object of the present invention.</li></ul>

0020A more detailed description of the method for backing up the local clock of a computer perimeter configured on a multicellular platform of computer resources, in accordance with the object of the present invention, will now be given in conjunction with the <figref idref="f0001">Figures 1a, 1b</figref> and with the following figures.

0021Prior to the actual description of the process which is the subject of the present invention, reminders will be indicated relative to the configuration and the operating mode of computer perimeters configured on a multicellular platform of computer resources.

0022With reference to the <figref idref="f0001">figure 1a</figref>, it is recalled that the current multicellular platforms can be constituted by hardware platforms conforming to the architecture Intel IA-64 for example.

0023In general, with reference to the above-mentioned figure, it is recalled that these multicellular platforms consist of cells denoted C_{K J}, k and j varying from 1 to N for example.

0024Such platforms in fact make it possible to configure IT perimeters P_i separate, at each perimeter P_j can be associated with an OS_i for example. Each OS_i then perceives its perimeter P_i as a platform independent of the size of the perimeter P_i.

0025OS operating systems_i may be different, their choice being made on the basis of technical requirements, depending on the operating activity considered, or criteria formulated by the user.

0026Each cell C_{K J} has basic IT resources such as notably resources marked R_kj can correspond to elements in memory, input / output elements or the like, as well as, of course, to a clock circuit denoted CK_{K J}.

0027Generally, a user is able to configure a perimeter P_i for the execution of an application or operating activity rated A_i, this perimeter P_i consisting of a plurality of cells as delimited for example on the <figref idref="f0001">figure 1a</figref>.

0028It is understood, in particular, that the user is able to configure one or more perimeters simultaneously on the platform considered PF as represented on the <figref idref="f0001">figure 1a</figref>, the perimeter P_{i + 1} allowing the execution for example of an operating activity A_{i + 1} for example separate from operating activity A_i. These configuration and partitioning operations of the multicellular platform can be executed by means of an administration tool denoted MT, itself provided with computer resources, and connected in network to the platform PF.

0029In general, at each perimeter P_i, we associate a local clock constituted by one of the CK clocks_{K J} of the constituent cells of the P perimeter_i.

0030When, of course, the IT perimeters P_i and P_{i + 1} are brought to operate simultaneously, the aforementioned perimeters are separated. So, with reference to the<figref idref="f0001">figure 1a</figref>, it is understood that the local clock of the perimeter P; consists of the clock and the clock circuits fitted to cell C_{K J} for example.

0031Finally, it is indicated that the administration tool MT is constituted by a software package executed by a computer system comprising, for example, a central unit UC_o, RAM working memory and CK clock_o, the whole being designated by Plateform Administration and Maintainability Sofware or PAM, as mentioned on the <figref idref="f0001">figure 1a</figref>.

0032It is thus understood that at each perimeter P_i can be associated with an OS_i for the execution of an application A_i.

0033Generally speaking, OS operating systems_i mentioned above allow access to the resources of the platform and in particular of the P perimeter_i through standard interfaces, these interfaces generally using either direct access, or via BIOS software, for Basic Input Output Software, to local hardware resources R_{K J} previously cited.

0034For this reason, on the <figref idref="f0001">figure 1b</figref>, we have represented a perimeter P_i allowing the execution of an operating activity A_i through an OS operating system_i, perimeter for which all the resources of the perimeter are noted Σ_{K J}R_{K J} where this notation designates the set of resources accessible via the OS operating system_i for the perimeter considered P_i, this perimeter being further associated with a so-called local clock Ck_i corresponding for example to one of the clocks of the constituent cells of the perimeter P_i.

0035For the implementation of the process which is the subject of the present invention, and in order to facilitate the implementation of the latter, the access interfaces to local resources are served either directly or via the BIOS, thanks to the setting implementation of the MT administration tool.

0036The corresponding architecture allows, as shown in <figref idref="f0001">figure 1b</figref>, to intercept the access of operating systems to the resources of the PF platform, the different perimeters P_i, P_{i + 1}, at P_{i + n} can be implemented on separate parts of the platform from similar or different operating systems and noted, for this reason, OS_i, OS_{i + 1} at OS_{i + n}.

0037It is further understood that, in accordance with a particularly remarkable aspect of the method which is the subject of the present invention, the user can also configure each perimeter P_i so that the successive perimeters are overlapped for example, each perimeter P_i at P_{i + n} may include, for example resources, that is to say C cells_{K J} municipalities, each perimeter then being used successively for the successive execution of the same application A_i for example.

0038It is understood, of course, that in such a situation in particular, the administration tool MT itself comprises computer resources and, of course, a clock denoted CK₀ on the <figref idref="f0001">figure 1b</figref>.

0039The object of the present invention is to allow the direct passage of a perimeter P_i to a separate perimeter P_{i + 1} and successively to successive separate perimeters for the execution of the same application A_i by successive passes from separate perimeters.

0040The process which is the subject of the present invention will now be described in conjunction with the <figref idref="f0002">figure 2a</figref> in the context previously cited.

0041With reference to the above-mentioned figure, it is indicated that the process which is the subject of the present invention allows the execution of an operating activity A_i on at least one current IT perimeter designated by P_i or on successive separate IT perimeters marked P_{i + 1} at P_{i + n} on the <figref idref="f0001">figure 1b</figref>.

0042In addition, with reference to the <figref idref="f0002">figure 2a</figref>, the method which is the subject of the invention consists, in a step A, of establishing for the assembly constituted by the administration tool MT and by all of the computer perimeters configurable on the multicellular platform, an absolute reference clock.

0043In step A of <figref idref="f0002">figure 2a</figref>, this operation is represented by the relation:         {CK₀, CK_{K J}} = CK_R.

0044By this relation, it is indicated that the process which is the subject of the present invention, in step A, consists in choosing, from among the set of local clocks which are present on the platform PF and, in particular, at the level of each cell C_{K J}, as well as among the CK clock₀ of the administration tool, a so-called reference clock making it possible to deliver absolute reference clock signals.

0045In general, it is indicated that the absolute reference clock CK_R allows to provide temporal information in the form of a reference date D_r and reference time H_r, this reference time information being designated by D_r/ H_r.

0046For each current computer perimeter, configured at the request of a user, with which is associated a current local clock making it possible to manage an operating activity from the operating system associated with this current perimeter, the method which is the subject of the invention. then consists, in step B, in calculating and memorizing, for each operating activity running on this current computer perimeter of the multicellular platform PF, a backup attribute containing, in addition to the time management parameters of the operating activity, and with reference to the current local clock delivering signals D_i/ H_i corresponding to date and time signals with reference to the current local clock, a time offset parameter noted δ_i, this parameter representing the offset of the time management parameters of the local clock with respect to the absolute reference clock.

0047In step B of the <figref idref="f0002">figure 2b</figref>, we note the relation:<maths id="math0001"><math display="block"><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">=</mo><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">+</mo><msub><mi mathvariant="normal">δ</mi><mi mathvariant="normal">i</mi></msub></math><img file="EP1324176B1_D0001.tif" /></maths> with:<maths id="math0002"><math display="block"><msub><mi mathvariant="normal">δ</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">=</mo><mi mathvariant="normal">VS</mi><mo>⁢</mo><msub><mi mathvariant="normal">K</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">-</mo><mi mathvariant="normal">VS</mi><mo>⁢</mo><msub><mi mathvariant="normal">K</mi><mi mathvariant="normal">R</mi></msub><mn mathvariant="normal">.</mn></math><img file="EP1324176B1_D0002.tif" /></maths>

0048We understand, in particular, that the time shift parameter δ_i is an algebraic parameter ahead or behind the absolute reference clock.

0049As a nonlimiting example, it is recalled that the local date values ​​D_i and absolute reference date D_r can advantageously be expressed in the form of: years YY, months MM, and days DD.

0050Likewise, the local time parameters H; and absolute reference time H_r can advantageously be expressed in the form of: hours, minutes, seconds and hundredths of a second, if necessary.

0051When, after stopping the execution of the operating activity A_i by the user, the latter reloads the same operating activity A_i on a separate perimeter according to P_{i + 1} for the continuation of the execution of this same operating activity A_i, these operations performed by the user being represented by the dotted line on the <figref idref="f0002">figure 2a</figref>, a separate local clock is, of course, necessarily associated with the following separate perimeter P_{i + 1}, which, in addition, can be managed by an OS operating system_{i + 1} separate from previous OS_i.

0052Under these conditions, the method which is the subject of the present invention consists, in a step C, in recalculating the time management parameters of the operating activity from the time offset parameter of the time management parameters. against the absolute reference clock.

0053In step C, we denote by D_{i + 1}/ H_{i + 1} the date parameters of the IT perimeter P_{i + 1}, the local clock CK_{i + 1} being the local clock associated with the IT perimeter following P_{i + 1}.

0054In step C, we calculate the date and time management parameters for the perimeter P_{i + 1} according to the relationship:<maths id="math0003"><math display="block"><msub><mi mathvariant="normal">D</mi><mrow><mi mathvariant="normal">i</mi><mo>+</mo><mn>1</mn></mrow></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mrow><mi mathvariant="normal">i</mi><mo>+</mo><mn>1</mn></mrow></msub><mo mathvariant="normal">=</mo><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">+</mo><msub><mi mathvariant="normal">δ</mi><mrow><mi mathvariant="normal">i</mi><mo>+</mo><mn>1</mn></mrow></msub><mn>.</mn></math><img file="EP1324176B1_D0003.tif" /></maths>

0055As in the case of the operation carried out in step B, the time offset verifies the relationship:<maths id="math0004"><math display="block"><msub><mi mathvariant="normal">δ</mi><mrow><mi mathvariant="normal">i</mi><mo>+</mo><mn>1</mn></mrow></msub><mo mathvariant="normal">=</mo><mi mathvariant="normal">VS</mi><mo>⁢</mo><msub><mi mathvariant="normal">K</mi><mrow><mi mathvariant="normal">i</mi><mo>+</mo><mn>1</mn></mrow></msub><mo mathvariant="normal">-</mo><mi mathvariant="normal">VS</mi><mo>⁢</mo><msub><mi mathvariant="normal">K</mi><mi mathvariant="normal">R</mi></msub><mn mathvariant="normal">.</mn></math><img file="EP1324176B1_D0004.tif" /></maths>

0056Step C is then followed by a step D consisting in updating the following local clock CK_{i + 1} associated with the following separate IT perimeter P_{i + 1} prior to the launch of operating activity A_i for further execution thereof.

0057In step D, the update operation is represented by the relation:<maths id="math0005"><math display="block"><msub><mfenced><msub><mi mathvariant="normal">D</mi><mrow><mi mathvariant="normal">i</mi><mo>+</mo><mn>1</mn></mrow></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mrow><mi mathvariant="normal">i</mi><mo>+</mo><mn>1</mn></mrow></msub></mfenced><mi mathvariant="normal">at</mi></msub><mo>⇔</mo><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">r</mi></msub><mn>.</mn></math><img file="EP1324176B1_D0005.tif" /></maths>

0058By the above-mentioned updating operation, represented by the double arrow, it is understood that this operation amounts to compensating for any deviation from each operating activity A_i and executed on the current IT perimeter then on the next separate IT perimeter P_{i + 1}.

0059In order to simplify the implementation of the method which is the subject of the present invention, this may consist, in step B, in carrying out a registration of the current local clock associated with the current perimeter P_i so as to compensate for the time difference δ_i during the execution of operating activity A_i on the current IT perimeter P_i.

0060On the <figref idref="f0002">figure 2b</figref>, this operation is carried out via a sub-step B1 consisting, of course, in calculating the time shift δ_i relative to the local reference clock, this operation in substep B1 being noted:<maths id="math0006"><math display="block"><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">=</mo><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">+</mo><msub><mi mathvariant="normal">δ</mi><mi mathvariant="normal">i</mi></msub></math><img file="EP1324176B1_D0006.tif" /></maths>

0061Sub-step B1 is then followed by a sub-step B2 consisting in carrying out a local update at the level of the perimeter P_i of the form verifying a relation:<maths id="math0007"><math display="block"><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">i</mi></msub><mo>⇔</mo><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">r</mi></msub><mn>.</mn></math><img file="EP1324176B1_D0007.tif" /></maths> this operation amounts to setting the local clock on the absolute reference clock.

0062Under these conditions, operation C can then be executed normally for the next separate IT perimeter P_{i + 1} and operation D then consists in carrying out an update on the basis of the only offset from the following distinct local clock, the value δ_i having been reduced to zero for the previous local clock of the current IT perimeter P_i.

0063Regarding the choice of local clock for each current IT perimeter P_i, then each separate IT perimeter P_{i + 1} at P_{i + n}, it is indicated that several possibilities can be envisaged.

0064According to a first possibility, the absolute reference clock can be constituted by a local hardware component of specific address belonging to the multicellular platform. In this situation, the method which is the subject of the present invention can consist in reserving one of the cells of the multicellular platform PF of determined address so as to reserve the local hardware component of the aforementioned cell and to assign to it ci the absolute reference clock function. Such a choice is possible, but it has the disadvantage of particularizing one of the C cells._{K J} of the PF platform and, finally, to impose one or more inputs / outputs and exchanges of messages between the administration tool MT and the platform PF to obtain the absolute clock information D_r/ H_r.

0065According to a preferred choice of implementation of the method which is the subject of the present invention, the absolute reference clock can advantageously be constituted by a local hardware component belonging to the administration tool.

0066Under these conditions, it is understood, of course, that the local component is none other than the clock CK₀ equipping the material resources of the MT administration tool.

0067This second solution appears preferable vis-à-vis the previous solution since the absolute reference clock being an integral part of the MT administration tool, it is no longer necessary to reserve the resources of a cell. specific to the PF platform on the one hand, while, on the other hand, the absolute reference clock and the corresponding signals are directly available at the level of the administration tool MT.

0068Finally, the process which is the subject of the present invention makes it possible, of course, to take into account any local modification of date and / or time which would be introduced voluntarily by the user during the execution of an operating activity A_i on an IT perimeter P_i corresponding.

0069Such date and / or time change operations are frequent and allow any user to use an arbitrary local time or, at the very least, likely to correspond to specific operating requirements.

0070For the implementation of the method which is the subject of the present invention during a voluntary local modification of date or time by the user, it is considered that the updating of the following distinct local clock, associated with the following distinct computing perimeter P_{i + 1}, was performed if necessary, in accordance with step D of the <figref idref="f0002">figure 2a</figref> and in step B of this same figure or, where appropriate and preferably, in accordance with the implementation of step B according to the <figref idref="f0002">figure 2b</figref>.

0071Under these conditions, it is indicated that the voluntary change of date and / or time is thus taken into account for any current IT perimeter P_i that it is configured by the user during the first implementation of application A_i or, where appropriate, during successive implementations.

0072Under these conditions, the process which is the subject of the present invention consists, as shown in the <figref idref="f0003">figure 2c</figref>, to modify the current local clock by a value corresponding to the modification introduced, this modification being noted Δ_i.

0073The current local clock modification operation checks the relationship:<maths id="math0008"><math display="block"><mo>-</mo><mfenced><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">i</mi></msub></mfenced><mo mathvariant="normal">=</mo><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">+</mo><msub><mi mathvariant="normal">Δ</mi><mi mathvariant="normal">i</mi></msub><mn>.</mn></math><img file="EP1324176B1_D0008.tif" /></maths>

0074Step E is then followed by a step F consisting in transmitting the value of the local modification of date and time Δ_i to the MT administration tool. The modification is requested from the BIOS by the OS_i managing the execution of operating activity A_i. The BIOS notifies the request to the MT administration tool.

0075On receipt of the aforementioned local modification value of date and time, the method which is the subject of the invention consists, in step G, in updating the time offset parameter of the time management parameters vis- against the absolute reference clock and the aforementioned backup attribute. This operation checks the relationship:<maths id="math0009"><math display="block"><msub><mfenced><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">i</mi></msub></mfenced><mi mathvariant="normal">at</mi></msub><mo mathvariant="normal">⇔</mo><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">r</mi></msub><mn mathvariant="normal">.</mn></math><img file="EP1324176B1_D0009.tif" /></maths>

0076This operation designates in fact the compensation of the date and time parameters and the setting of the corresponding values ​​on the date and time values ​​of the reference clock, as mentioned previously in the description.

0077Means of specific implementation of the process which is the subject of the present invention will now be described in conjunction with the <figref idref="f0003 f0004">figures 3a to 3c</figref>, then 3d and 3e for the operations carried out during changes to the current IT perimeter P; in a separate IT perimeter P_{i + 1} respectively a voluntary change of date and time made by the user, during the execution of an operating activity A; on a current IT perimeter P_i.

0078The <figref idref="f0003">figure 3a</figref> represents the operations carried out when the operating activity A was created_i.

0079The MT administration tool and, in particular, the corresponding PAM software, create an Identity type computer file or object dedicated to operating activity A_i cited above. This file can advantageously include, as shown in the<figref idref="f0003">figure 3a</figref>, the name of the operating activity A_i as well as a default time offset setting δ_i established at zero value with respect to the reference clock D_r/ H_r. The administration tool MT can then collect a plurality of identity files or identity files corresponding to different activities.

0080The <figref idref="f0003">figure 3b</figref> represents the loading process of operating activity A_i on the perimeter P; user defined.

0081At the time of initialization of the perimeter P_i above, the administration tool MT then calculates the effective value of the time offset δ_i according to the relationship shown in step B of the <figref idref="f0002">figure 2a</figref> or, if applicable, according to step B1 of the <figref idref="f0002">figure 2b</figref>.

0082The administration tool MT transmits the information necessary for updating the local clock of the PSTN clock component of the perimeter P_i through the BIOS. This operation is then carried out according to step B2 of the<figref idref="f0002">figure 2b</figref>.

0083The BIOS software then performs the update according to the relation of step B2 of the <figref idref="f0002">figure 2b</figref> before handing over to the OS_i under which the operating activity A is carried out_i.

0084The <figref idref="f0004">figure 3c</figref> represents the operations carried out during the introduction of a modification of date and / or time by the user of the operating activity A_i as shown in <figref idref="f0003">figure 2c</figref>.

0085First, the user of operating activity A; requests the modification of the management parameters of the current time D_i/ H_i.

0086The SetTime method of the BIOS EFI interface is then called with the parameters of the date and / or time modification request.

0087The perimeter BIOS P_i updates the local clock component CKi of the IT perimeter P_i and transmits the parameters of the modification request to the administration tool MT.

0088The MT administration tool and, in particular, the PAM software module thereof, then recalculate the difference corresponding to the modification Δ_i and checking the relationship:<maths id="math0010"><math display="block"><msub><mi mathvariant="normal">Δ</mi><mi mathvariant="normal">i</mi></msub><mo>=</mo><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">i</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">i</mi></msub><mo>-</mo><msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">r</mi></msub><mo mathvariant="normal">/</mo><msub><mi mathvariant="normal">H</mi><mi mathvariant="normal">r</mi></msub></math><img file="EP1324176B1_D0010.tif" /></maths> between the new date and time parameter resulting from the modification and the reference time and updates the date and time attribute of the identity object whose name corresponds to activity A_i.

0089The <figref idref="f0004">3d figure</figref> represents the operations executed during the cessation of the execution of an operating activity on a current IT perimeter P_i previously performing an operating activity A_i.

0090With reference to the <figref idref="f0004">3d figure</figref> mentioned above, when such an activity is stopped and in fact it frees the IT perimeter P_i used, the identity object is saved by the MT administration tool.

0091The <figref idref="f0005">figure 3e</figref> represents the loading of operating activity A_i previous on a new IT perimeter P_{i + 1}.

0092The treatments performed in this situation are then identical to the operations performed and described when loading activity A_i on the IT perimeter P_i represented in <figref idref="f0003">figure 3b</figref>. However, as part of the<figref idref="f0005">figure 3e</figref>, the operations are carried out this time via the BIOS of the IT perimeter P_{i + 1}. Ultimately, activity A_i has changed perimeter while retaining, however, the modification of time and date made on the previous perimeter, as described previously in connection with the <figref idref="f0003">figure 3b</figref> where the <figref idref="f0004">figure 3c</figref> when it is a voluntary modification.

0093Finally, with reference to the <figref idref="f0005">figure 4</figref>, it is indicated that a system for backing up the local clock of a computer perimeter, in accordance with the object of the present invention, comprises, in particular, an absolute reference clock circuit denoted CK_R, this circuit being able to be chosen from one of the clock circuits equipping the computer platform PF or, preferably, as represented on the <figref idref="f0005">figure 4</figref>, the computer that makes up the MT administration tool.

0094In addition, the system which is the subject of the invention is remarkable in that the administration tool MT comprises, located in permanent memory of the computer, that is to say either in ROM memory or on the hard disk. of the latter, a module for calculating a backup attribute containing, in addition to the time management parameters of the operating activity A; with reference to the local clock CK_i, a time shift parameter of the time management parameters with respect to the absolute reference clock CK_R.

0095It is understood, in particular, that the aforementioned calculation module can be constituted by a program stored in the form of a file in the hard disk or, if necessary, in ROM read only memory and loaded when the administration tool is initialized MT. This module therefore consists of a software module denoted F₁ on the <figref idref="f0005">figure 4</figref>.

0096In addition, a CK local clock update module_i of any partition P_i is also provided, in accordance with the relationships previously given in the description for the implementation of the process which is the subject of the present invention. This module is represented by an F file₂ on the <figref idref="f0005">figure 4</figref>, which is also loaded into the computer's main memory upon initialization.

0097Preferably, the backup attribute consists of an Identity file comprising at least the name of the operating activity A_i and the time value associated with this operating activity, for the IT perimeter P_i considered.