Upgrading and downgrading method based on local storage engine system and local storage engine system

Abstract

The invention discloses an upgrading and degrading method based on a local storage engine system, the local storage engine system comprises a first version and a second version, and the second version is higher than the first version. The upgrading and degrading method based on the local storage engine system comprises the following steps: setting a first version as a first space management mode based on an operation log and a first space manager; setting the second version as a second space management mode based on a second space manager; before upgrading, the first version is promoted to a transition stage, and a third space management mode based on the operation log and the second space manager is adopted in the transition stage; and executing upgrading operation in the transition stage, upgrading to the second version if the upgrading operation succeeds, and returning to the first version if the upgrading operation fails. Operation and maintenance risk points caused by the fact that a local storage engine system lacks an effective degradation function to deal with abnormal conditions when the distributed storage system is upgraded can be eliminated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of distributed storage, and particularly relates to a promotion and demotion method based on a local storage engine system and the local storage engine system. BACKGROUND

[0002] With the development of cloud computing, distributed storage systems are constantly evolving. In addition to capacity and performance, the maintainability of distributed storage systems is also increasingly concerned. The mainstream distributed storage systems mostly use self-managed bare disks to improve the performance of local storage engines, optimize distributed storage systems, and provide better support for new storage devices. The local storage engine system based on self-managed bare disks needs to manage bare disk space by itself. When the way of managing bare disk space changes in different versions, the local storage engine system can mostly support upgrading, but the demotion function is imperfect or even not supported, which exposes a maintenance risk point of the local storage engine system during upgrading: lack of effective demotion function to roll back the version to cope with abnormal situations, which also brings risks to the maintenance of the distributed storage system. SUMMARY

[0003] In view of the above-mentioned deficiencies existing at present, the present application provides a promotion and demotion method based on a local storage engine system and the local storage engine system, so as to eliminate the maintenance risk point during the upgrading of the distributed storage system due to the lack of effective demotion function of the local storage engine system to roll back the version to cope with abnormal situations.

[0004] To achieve the above-mentioned purpose, the embodiments of the present application adopt the following technical solutions: A promotion and demotion method based on a local storage engine system, the local storage engine system comprising a first version and a second version, the second version being higher than the first version, the promotion and demotion method based on the local storage engine system comprising the following steps: Setting the first version as a first space management mode based on an operation log and a first space manager; Setting the second version as a second space management mode based on a second space manager; Before upgrading, first promoting the first version to a transition stage, and in the transition stage, the third space management mode based on the operation log and the second space manager; Performing an upgrading operation in the transition stage, and if successful, upgrading to the second version, and if failed, rolling back to the first version.

[0005] According to an aspect of the present application, the setting of the first version as the first space management mode based on the operation log and the first space manager comprises: dividing the local storage disk space into multiple spaces, and the first space manager comprising a space management module established for each space.

[0006] According to one aspect of the present application, the plurality of spaces at least comprises a metadata space for storing metadata and a data space for storing data, and the first space manager at least comprises a metadata space management module and a data space management module.

[0007] According to one aspect of the present application, the first space management mode comprises: at startup, reading metadata application and space release operation logs from the operation log, obtaining the space as a metadata space and handing it over to the metadata space management module for management; the remaining space is a data space, which is handed over to the data space management module for management.

[0008] According to one aspect of the present application, the first space management mode comprises: if the metadata space is sufficient, the metadata space application and release are managed by the metadata space management module when writing or deleting metadata, and no operation log is generated; if the metadata space is insufficient, the metadata space application and release are managed by the metadata space management module when writing or deleting metadata, and no operation log is generated.

[0009] According to one aspect of the present application, the first space management mode comprises: a metadata space threshold is preset, and when the metadata is deleted to exceed the threshold, the space of the threshold size is released from the metadata space to the data space, and the corresponding operation log is generated.

[0010] According to one aspect of the present application, the first space management mode comprises: when writing or deleting data, the data space application and release are managed by the data space management module, and no operation log is generated.

[0011] According to one aspect of the present application, the second space management mode comprises: the local storage disk space is handed over to the second space manager for management, and no operation log is generated when the metadata application and release space; at startup, the second space manager data is read to update the second space manager.

[0012] According to one aspect of the present application, the second space management mode comprises: when writing metadata, the second space manager is applied to free space to store metadata; when deleting metadata, the second space manager releases the specific metadata space; when writing data, the second space manager is applied to free space to store data; when deleting data, the second space manager releases the specific data space.

[0013] According to an aspect of the present application, the space management mode based on the operation log and the second space manager in the transition stage comprises: handing over the local storage disk space to the second space manager for management, reading the first version of the operation log from the operation log at startup, managing the space by the second space manager according to the operation log, and reading the first version of the first space manager data to update the second space manager.

[0014] According to an aspect of the present application, the third space management mode comprises: managing the application and release of the metadata space by the second space manager when writing or deleting metadata, and generating the corresponding operation log.

[0015] According to an aspect of the present application, the third space management mode comprises: applying for the free space to store data to the second space manager when writing data; and releasing the specific data space by the second space manager when deleting data.

[0016] According to an aspect of the present application, the upgrade operation is performed in the transition stage, and the downgrade operation is no longer supported after successful upgrade to the second version; the upgrade operation is performed in the transition stage, and the downgrade operation can be performed again after failure to return to the first version.

[0017] A local storage engine system, which is upgraded and downgraded by the upgrade and downgrade method based on the local storage engine system as described above.

[0018] Advantages of the present application: 1. The high-version space management of the local storage engine system is more concise and efficient, and has lower implementation difficulty than the low-version.

[0019] 2. In the upgrade transition stage of the local storage engine system, a small cost of one more operation log for metadata application and release space is used to compatible the space management modes of the low-version and the high-version of the local storage engine system, and to realize the upgrade and downgrade functions between the low-version and the high-version of the local storage engine system.

[0020] 3. The data written in the upgrade transition stage of the local storage engine system can be normally read in the high-version after upgrade and the low-version after downgrade, which guarantees the integrity of the data.

[0021] 4. The local storage engine system is provided with a downgrade method under two specific bare disk space management modes, which eliminates the operation and maintenance risk points due to the lack of effective downgrade function of the local storage engine system to return to the version to deal with abnormal situations. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only show some of the embodiments of the present application, and other drawings can be obtained by those of ordinary skill in the art without any creative effort based on these drawings.

[0023] Figure 1 A schematic diagram of a low-version bare disk space management mode of the local storage engine system described in the present application; Figure 2 A schematic diagram of a high-version bare disk space management mode of the local storage engine system described in the present application; Figure 3 A schematic diagram of a transition stage bare disk space management mode of the local storage engine system described in the present application when the low version is upgraded to the high version; Figure 4 A schematic diagram of an upgrade and downgrade process between the low version and the high version of the local storage engine system described in the present application. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative effort fall within the scope of the present application.

[0025] Embodiment one As shown in Figure 1 , Figure 2 , Figure 3 and Figure 4 , a local storage engine system-based upgrade and downgrade method, the local storage engine system including a first version and a second version, the second version being higher than the first version, that is, the first version is a low version and the second version is a high version, the local storage engine system-based upgrade and downgrade method including the following steps: Step S1: setting the first version as a first space management mode based on an operation log and a first space manager; The setting of the first version as the first space management mode based on the operation log and the first space manager includes dividing the local storage disk space into multiple spaces, the first space manager including a space management module established for each space. The multiple spaces include at least a metadata space for storing metadata and a data space for storing data, and the first space manager includes at least a metadata space management module and a data space management module.

[0026] In practical application, the first space management mode includes: at start, reading metadata application and releasing space operation log from operation log, obtaining space as metadata space, and handing over to metadata space management module for management; remaining space as data space, handing over to data space management module for management.

[0027] In practical application, the first space management mode includes: if metadata space is sufficient, managing metadata space application and releasing by metadata space management module when writing or deleting metadata, without generating operation log; if metadata space is insufficient, applying space to metadata space from data space management module when writing or deleting metadata, and generating corresponding operation log.

[0028] In practical application, the first space management mode includes: presetting metadata space threshold, releasing space of threshold size from metadata space to data space when metadata is deleted to exceed threshold, and generating corresponding operation log.

[0029] In practical application, the first space management mode includes: managing data space application and releasing by data space management module when writing or deleting data, without generating operation log.

[0030] In the embodiment, the first version is low version, local storage space in low version is bare disk space, space management module is space allocator, metadata space management module is metadata space allocator, and data space management module is data space allocator; specific bare disk space is metadata space and data space, and specific first space management mode is as follows: 1. At initialization of local storage engine system, a piece of space is cut out from bare disk space for storing metadata, and an operation log OP_ALLOC_ADD of applying space is generated; remaining space is used for storing data. Metadata and data bare disk space are managed by respective space allocators.

[0031] 2. At start of local storage engine system, reading OP_ALLOC_ADD and OP_ALLOC_RM, two kinds of metadata application and releasing space operation logs from operation log, merging space applied and released by the two kinds of operation logs according to order, obtaining final applied space, handing over the space as metadata bare disk space to metadata space allocator for management; remaining bare disk space as data bare disk space, handing over to data space allocator for management. Then reading metadata space allocator data to update metadata space allocator, and reading data space allocator data to update data space allocator.

[0032] 3. When writing metadata, the metadata space allocator is applied to store metadata in free space, and no operation log OP_ALLOC_ADD of applying space is generated; when deleting metadata, the metadata space allocator releases specific metadata space, and no operation log OP_ALLOC_RM of releasing space is generated.

[0033] 4. When the metadata space is insufficient, a piece of free space is applied to the data space allocator to join the metadata raw disk space, and an operation log OP_ALLOC_ADD of applying space is generated.

[0034] 5. When the metadata is deleted in large quantities, the free space in the metadata space allocator exceeds the set threshold size, the free space of the set threshold size is removed from the metadata space allocator, and then the removed space is added to the data space allocator, and an operation log OP_ALLOC_RM of releasing space is generated.

[0035] 6. When writing data, the data space allocator is applied to store data in free space, and no operation log OP_ALLOC_ADD of applying space is generated; when deleting data, the data space allocator releases specific data space, and no operation log OP_ALLOC_RM of releasing space is generated.

[0036] Step S2: Set the second version as a second space management mode based on the second space manager; The second space management mode includes: handing over the local storage disk space to the second space manager for management, and not generating operation logs when the metadata applies and releases space; reading the second space manager data to update the second space manager when starting.

[0037] In actual application, the second space management mode includes: when writing metadata, applying free space to the second space manager to store metadata; when deleting metadata, the second space manager releases specific metadata space; when writing data, applying free space to the second space manager to store data; when deleting data, the second space manager releases specific data space.

[0038] In this embodiment, the second version is a high version, and the local storage space in the high version is a raw disk space. The second space manager is a global space allocator, and the specific second space management mode is as follows: 1. When the local storage engine system is initialized, the raw disk space of metadata and data is not distinguished, but the entire raw disk space is handed over to a global space allocator for management, and no operation logs OP_ALLOC_ADD and OP_ALLOC_RM of applying and releasing space are generated when the metadata applies and releases space.

[0039] 2. Local storage engine system starts, read global space allocator data to update global space allocator.

[0040] 3. When writing metadata, the global space allocator is applied for free space to store metadata; when deleting metadata, the global space allocator releases the specific metadata space.

[0041] 4. When writing data, the global space allocator is applied for free space to store data; when deleting data, the global space allocator releases the specific data space.

[0042] Step S3: Before upgrading, the first version is promoted to a transition phase, and the third space management mode based on the operation log and the second space manager is provided in the transition phase; The space management mode based on the operation log and the second space manager in the transition phase includes: the local storage disk space is managed by the second space manager, and when starting, the operation log of the first version is read from the operation log, and the second space manager manages the space according to the operation log, and the first space manager data of the first version is read to update the second space manager.

[0043] In practical application, the third space management mode includes: when writing or deleting metadata, the second space manager manages the application and release of metadata space, and generates the corresponding operation log.

[0044] In practical application, the third space management mode includes: when writing data, the second space manager is applied for free space to store data; when deleting data, the second space manager releases the specific data space.

[0045] When the local storage engine system is upgraded from a low version to a high version, it first enters a transition phase, at which time it can be upgraded to a high version, but no longer supports downgrading; it can also be downgraded to a low version.

[0046] 1. When the local storage engine system starts, it does not distinguish between metadata and data bare disk space, but manages the entire bare disk space by a global space allocator. Read OP_ALLOC_ADD and OP_ALLOC_RM operation logs of two types of low version metadata space allocation and release operations from the operation log, and then the global space allocator sequentially allocates (corresponding to OP_ALLOC_ADD operation log) or releases (corresponding to OP_ALLOC_RM operation log) the space corresponding to the operation log according to the reading order; avoid allocating free space from the local storage engine system low version metadata bare disk space to store data or metadata, resulting in loss of data when downgrading to the local storage engine system low version. Then read the low version metadata space allocator data and data space allocator data to update the global space allocator.

[0047] 2. When writing metadata, the global space allocator is applied to allocate specific space to store metadata, and an operation log OP_ALLOC_ADD of applying space is generated; when deleting metadata, the global space allocator releases the specific metadata space, and an operation log OP_ALLOC_RM of releasing space is generated. The operation log generated by applying and releasing metadata space is to identify the change of metadata space in the transition stage when downgrading to the low version of the local storage engine system, so as to ensure the integrity of data.

[0048] 3. When writing data, the global space allocator is applied to allocate specific space to store data; when deleting data, the global space allocator releases the specific data space.

[0049] Step S4: Perform the upgrade operation in the transition stage, and if successful, upgrade to the second version, and if failed, return to the first version.

[0050] After the upgrade operation in the transition stage is successful and the local storage engine system is upgraded to the second version, the downgrade operation is no longer supported; after the upgrade operation in the transition stage fails and the local storage engine system returns to the first version, the local storage engine system can be upgraded again.

[0051] After the local storage engine system is upgraded from the transition stage to the high version, the downgrade is no longer supported, and at this time, the local storage engine system works according to the second space management mode described in step S2, that is, the high version space management mode, and can normally read the data written in the low version and the transition stage. After the local storage engine system is downgraded from the transition stage to the low version, the local storage engine system works according to the first space management mode described in step S1, that is, the low version space management mode, and can normally read the data written in the low version and the transition stage, and can be upgraded again subsequently.

[0052] Specifically, the implementation process of the present application is as follows: The first aspect, as shown in the figure, the low version space management mode of the local storage engine system: Figure 1 1. When the local storage engine system is initialized, a piece of space h~l is cut out from the raw disk space for storing metadata, and an operation log OP_ALLOC_ADD of applying space is generated; the remaining spaces a~h and l~s are used for storing data. The raw disk spaces of metadata and data are managed by respective space allocators.

[0053] ​2. The local storage engine system starts, reads the OP_ALLOC_ADD and OP_ALLOC_RM metadata from the operation log, and merges the two types of operation logs to apply and release space in sequence. The final applied space is obtained, and the space obtained after the first initialization is h~l. The space is used as metadata raw disk space and is managed by the metadata space allocator. The remaining raw disk space is used as data raw disk space, and the data space obtained after the first initialization is a~h and l~s, which is managed by the data space allocator. Then, the metadata space allocator data is read to update the metadata space allocator, and the data space allocator data is read to update the data space allocator.

[0054] 3. When writing metadata, free space (e.g., j~k) is applied to the metadata space allocator to store metadata, and no operation log OP_ALLOC_ADD is generated to apply space. When deleting metadata, the metadata space allocator releases specific metadata space (e.g., h~i), and no operation log OP_ALLOC_RM is generated to release space.

[0055] 4. When the metadata space is insufficient, a piece of free space (e.g., m~p) is applied to the data space allocator to join the metadata raw disk space, and an operation log OP_ALLOC_ADD is generated to apply space. At this time, the metadata space has h~l and m~p, and the data space has a~h, l~m, and p~s.

[0056] 5. When the metadata is deleted in large quantities, and the free space in the metadata space allocator exceeds the set threshold size, the set threshold size of free space is removed from the metadata space allocator, and then the removed space is added to the data space allocator, and an operation log OP_ALLOC_RM is generated to release space. For example, space h~l is idle and meets the set threshold size, so it is removed from the metadata space allocator and added to the data space allocator. At this time, the metadata space has m~p, and the data space has a~m and p~s.

[0057] 6. When writing data, free space (e.g., b~c) is applied to the data space allocator to store data, and no operation log OP_ALLOC_ADD is generated to apply space. When deleting data, the data space allocator releases specific data space (e.g., d~e), and no operation log OP_ALLOC_RM is generated to release space.

[0058] Secondly, as shown in Figure 2 the local storage engine system high version space management method: 1. Local storage engine system initialization, no distinction between metadata and data of the bare disk space, but the whole bare disk space a~s as a global space allocator to manage, metadata application, release space no longer generate operation log OP_ALLOC_ADD, OP_ALLOC_RM.

[0059] 2. Local storage engine system startup, read global space allocator data to update the global space allocator.

[0060] 3. When writing metadata, it will apply for free space (for example j~k ) to store metadata to the global space allocator; when deleting metadata, the global space allocator will release the specific metadata space (for example h~i ).

[0061] 4. When writing data, it will apply for free space (for example b~c ) to store data to the global space allocator; when deleting data, the global space allocator will release the specific data space (for example d~e ).

[0062] Thirdly, as shown in Figure 3 The local storage engine system is upgraded from a low version to a high version, first enters a transition stage, at this time it can be upgraded to a high version, but no longer supports downgrading; it can also be downgraded to a low version. The local storage engine system transition stage bare disk space management method: 1. Local storage engine system startup, no distinction between metadata and data of the bare disk space, but the whole bare disk space a~s as a global space allocator to manage. Read OP_ALLOC_ADD and OP_ALLOC_RM, two types of low version metadata space application and release operation logs, then the global space allocator applies (corresponding to OP_ALLOC_ADD operation log) or releases (corresponding to OP_ALLOC_RM operation log) the space corresponding to the operation log (for example h~l and m~p ) in order according to the reading sequence; avoid applying free space to store data or metadata from the local storage engine system low version metadata bare disk space (for example h~l and m~p ), resulting in data loss when downgrading to the local storage engine system low version. Then read the low version metadata space allocator data and data space allocator data to update the global space allocator.

[0063] 2. When writing metadata, the global space allocator is applied to allocate specific space (e.g. f~g) to store metadata, and an operation log OP_ALLOC_ADD of applying space is generated; when deleting metadata, the global space allocator releases the specific metadata space (e.g. h~i), and an operation log OP_ALLOC_RM of releasing space is generated. The operation log of applying and releasing metadata space is generated to identify the change of metadata space in the transition phase when downgrading to the low version of the local storage engine system, so as to ensure the integrity of data.

[0064] 3. When writing data, the global space allocator is applied to allocate specific space (e.g. b~c) to store data; when deleting data, the global space allocator releases the specific data space (e.g. d~e).

[0065] In the fourth aspect, as shown in FIG. 4, the local storage engine system is upgraded from the transition phase to the high version, and no longer supports downgrading. At this time, the local storage engine system works according to the high version space management manner described in the second aspect, and can normally read the data written in the low version and the transition phase. The local storage engine system is downgraded from the transition phase to the low version. At this time, the local storage engine system works according to the low version space management manner described in the first aspect, and can normally read the data written in the low version and the transition phase, and can be upgraded again subsequently. Figure 4

[0066] Embodiment Two A local storage engine system includes a local storage bare disk space, and the local storage engine system is upgraded and downgraded by using the upgrade and downgrade method based on the local storage engine system described in Embodiment One.

[0067] 1. The local storage engine system self-manages the bare disk, and the low version and the high version have different space management manners.

[0068] 2. When the local storage engine system is upgraded from the low version to the high version, there is an upgrade transition phase. In the transition phase, the local storage engine system can be upgraded to the high version and no longer supports downgrading; or the local storage engine system can be downgraded to the low version, and can be upgraded again subsequently.

[0069] 3. The space management manner of the upgrade transition phase of the local storage engine system is different from the low version and the high version, and is compatible with the space management manners of the low version and the high version.

[0070] 4. The local storage engine system supports writing data in the upgrade transition phase, and the written data can be normally read in the high version after upgrading and in the low version after downgrading.

[0071] ​5. The local storage engine system upgrade transition phase does not apply space from the low version metadata bare disk space, and all metadata space application and release operations generate operation logs, which are the key to compatibility between low and high version space management methods.

[0072] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which shall be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for upgrading a local storage engine system based on a first version and a second version, the second version being higher than the first version, the method comprising: The promotion and demotion method based on the local storage engine system comprises the following steps: Setting a first version as a first space management mode based on an operation log and a first space manager; Setting a second version as a second space management mode based on a second space manager; Before the promotion, the first version is promoted to a transition stage, and the third space management mode based on the operation log and the second space manager is used in the transition stage; If the promotion operation in the transition stage is successful, the second version is promoted, and if the promotion operation in the transition stage fails, the first version is demoted.

2. The demotion method based on a local storage engine system according to claim 1, wherein, The first version is set as the first space management mode based on the operation log and the first space manager, which comprises dividing the local storage disk space into multiple spaces, and the first space manager comprises a space management module established for each space.

3. The demotion method based on a local storage engine system according to claim 2, wherein, The multiple spaces comprise at least a metadata space for storing metadata and a data space for storing data, and the first space manager comprises at least a metadata space management module and a data space management module.

4. The demotion method based on a local storage engine system according to claim 3, wherein, The first space management mode comprises the following steps: when starting, reading the metadata application and the operation log of the released space from the operation log, obtaining the space as the metadata space, and handing over the metadata space to the metadata space management module for management; the remaining space is handed over to the data space management module for management.

5. The demotion method based on a local storage engine system according to claim 4, wherein, The first space management mode comprises the following steps: if the metadata space is sufficient, the metadata space application and release are managed by the metadata space management module when writing or deleting metadata, and no operation log is generated; if the metadata space is insufficient, the space is applied to the data space management module when writing or deleting metadata, and the corresponding operation log is generated.

6. The demotion method based on a local storage engine system according to claim 4, wherein, The first space management mode comprises the following steps: presetting a metadata space threshold, and releasing the space with the threshold size from the metadata space to the data space when the metadata is deleted to exceed the threshold, and generating the corresponding operation log.

7. The demotion method based on a local storage engine system according to claim 4, wherein, The first space management mode comprises the following steps: when writing or deleting data, the data space application and release are managed by the data space management module, and no operation log is generated.

8. The demotion method based on a local storage engine system according to claim 1, wherein, The second space management mode comprises the following steps: handing over the local storage disk space to the second space manager for management, and generating no operation log when the metadata application and release space; when starting, reading the second space manager data to update the second space manager.

9. The promotion / demotion method based on a local storage engine system according to claim 8, wherein, The second space management mode comprises the following steps: when writing metadata, applying the idle space to the second space manager to store the metadata; when deleting metadata, the second space manager releases the specific metadata space; when writing data, applying the idle space to the second space manager to store the data; and when deleting data, the second space manager releases the specific data space.

10. The demotion method based on a local storage engine system according to any one of claims 1 to 9, characterized in that, The space management mode based on the operation log and the second space manager in the transition stage comprises the following steps: handing over the local storage disk space to the second space manager for management, reading the operation log of the first version from the operation log when starting, and reading the first space manager data of the first version to update the second space manager according to the operation log.

11. The demotion method based on a local storage engine system according to claim 10, wherein, The third space management mode comprises: when writing or deleting metadata, the application and release of the metadata space are managed by the second space manager, and the corresponding operation log is generated.

12. The demotion method based on a local storage engine system according to claim 10, wherein, The third space management mode comprises: when writing data, the second space manager is applied for free space to store data; when deleting data, the second space manager releases the specific data space.

13. The demotion method based on a local storage engine system according to claim 10, wherein, The upgrade operation is performed in the transition phase, and after successful upgrade to the second version, the downgrade operation is no longer supported; The upgrade operation is performed in the transition phase, and after failure to return to the first version, the upgrade can be performed again.

14. A local storage engine system, characterized by, The local storage engine system adopts the upgrade and downgrade method based on the local storage engine system in claims 1 to 13 for upgrade and downgrade management.

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