System Migration by using SOBAR
Relocating the files from the IBM Storage Scale file system managed by IBM Storage Archive, to a new file system without recalling the files back from the tapes.
About this task
- By using the system migration using SOBAR feature, you can relocate the files from the IBM Storage Scale file system that is managed by IBM Storage Archive EE, to a new file system without recalling the files back from the tapes.
- This feature is supported from IBM Storage Archive EE 1.3.2.
IBM Storage Archive EE implements migrating one system into another new IBM Storage Archive EE system with Scale out backup and restore (SOBAR) function of IBM Storage Scale. For more information on SOBAR feature, see https://www.ibm.com/docs/en/spectrum-scale/5.1.1?topic=administering-scale-out-backup-restore-sobar on IBM Storage Scale IBM documentation.
When a file in the IBM Storage Scale file system is migrated to tape, it appears exactly as it did before, though the file entity is truncated after being copied to tape and the file on disk becomes a stub file. This method presents a problem when transferring the entire contents of a file system to a new file system if the original file system contains many stub files. This is because the traditional file copy tool is unaware of the stub file and attempts to copy the file from the source file system to the target file system, which causes the file entity to be recalled from the tape. The recall operation is time-consuming, and some disk space is also required during the transition between systems.
- Back up the IBM Storage Archive EE configuration information on the existing system.
- Create the snapshot image of IBM Storage Scale file system metadata, and reconstruct the files and directories on the new IBM Storage Scale file system from the image.
- Deprive the old system of the right of controlling the tapes, and give the right to the new system, and configure new IBM Storage Archive cluster with the taken over tape and backed up configuration information.
- Make the tapes accessible from the newly created file system.
- Copy the file entity of resident files from the source file system to the target file system.
The use of System Migration using SOBAR feature requires prior review and consultation by IBM. You can contact IBM Support for more detailed instructions. The procedure uses a portion of SOBAR function in IBM Storage Scale, and new commands of IBM Storage Archive EE, and all the operation must follow the exact sequence of commands in the procedure.
High-level overview of system migration procedure
| Operation | Explanation |
|---|---|
| Generate files with SOBAR | Use the SOBAR command and create some files that are used for restoring. |
| Transfer files to temporary space | Copy the files to the Temporary Space. |
| Restore file system | Restore Storage Scale file system. |
| Image restore | Call mmimgrestore command with SOBAR image file. |
| Restore EE | Restore with backed up IBM Storage Archive EE meta/config files. |
| Transfer to target | Transfer Resident file entities to the target file system from Temporary Space or Source file system. |
| Term | Explanation |
|---|---|
| Source Storage Scale Cluster |
The IBM Storage Scale cluster from which the files are relocated to new cluster by using system migration feature. The cluster might include some file systems, which are not related to IBM Storage Archive EE. These file systems are not supported by system migration function. |
| Target Storage Scale Cluster |
This is the cluster of relocated system and must not have any file systems before restoring. |
| Temporary Space |
This storage doesn’t belong to the source IBM Storage Scale file system and the target file system but is part of the target system (for example: a local disk of a target server). The required capacity of this storage depends on whether you directly transfer Resident file entities and the size of the files in your source cluster. |
| Tape Library |
The tape library, which is operated by the source IBM Storage Archive EE. You can transfer the source cluster to the target cluster without any operations for the tapes, pools, and tape library. |
| Term | Explanation |
|---|---|
| Resident file entities |
This term is used to distinguish between the files and SOBAR-restored resident files. SOBAR doesn't restore resident files entities, therefore must be copied manually. |
| EE meta/config files |
Meta or config files of the source IBM Storage Archive EE system. You must copy the files to temporary space manually. |
| SOBAR config backup file | This file is generated by mmbackupconfig command. You must restore the source file system at the target file system with this file. |
| SOBAR image file | This file is generated by mmimgbackup command. This is used for restoring migrated stub files (SOBAR-restored migrated file stubs). |
| Restored EE meta/config files | These files are created by ltfsee_config command with transferred and backed up IBM Storage Archive EE files. |
| SOBAR-restored resident files | These files are created by mmimgrestore command, if there are any resident files at source file system when mmimgbackup command is called. The contents of these files are all zero. |
| SOBAR-restored migrated file stubs | These files are created by mmimgrestore command, if there are any migrated files at source file system when mmimgbackup command is called. |
Typical use case Scenario
There is no method to replace the library or the drives while migrating system with the System Migration by using SOBAR feature. If you want to replace the library and the drives, refer Replacing a library after completing all operations of System Migration by using SOBAR.
- Use case 1
- Migrating the current IBM Storage Archive
EE system into another new system.
- The migration is performed between two different IBM Storage Scale clusters.
- Use case 2
- Replacing IBM Storage Scale disk.
- You can complete the replacement within one IBM Storage Scale cluster.