Flashes (Alerts)
Abstract
A Scale Out Backup And Restore (SOBAR) restore using IBM Spectrum Scale or the General Parallel File System (both called GPFS in the following) can lead to the loss of files.
Content
Affected files are migrated with IBM Spectrum Protect for Space Management or Tivoli Storage Manager for Space Management (both called HSM in the following). These files are deleted in the storage pool used for HSM on the Tivoli Storage Manager server or IBM Spectrum Protect server (both called TSM server in the following). The deletion is triggered by HSM's reconciliation. This problem occurs when the file system identifiers of the file system used for SOBAR backup and SOBAR restore differ.
This problem is addressed by APAR IT17390.
The following sequence of events leads to this problem when an affected HSM level is used:
- A SOBAR restore is performed to a GPFS different from the one used for the SOBAR backup. - Note: When the GPFS used for backup had been recreated after the backup, then the file system identifiers differ.
- Reconciliation runs in default (FILEINFO) mode or Two-Way Orphan check (TWO) mode. - Note: When the TWO mode is configured, typically the GPFS policy engine is used.
- The time interval specified for the MIGFILEEXPIRATION option elapsed
4. Reconciliation runs again in default or TWO mode.
Note: Restores do not lead to this problem, if the backup-archive client is invoked directly without using SOBAR.
Possible consequences of the problem
- affected files can not be recalled using HSM
- affected files are lost unless backup copies exist
Affected HSM levels:
| Affected releases | Affected levels | Fixing levels |
| 6.4 | 6.4.1.0 through 6.4.3.3 | AIX GPFS 6.4.3.4 Linux x86 6.4.3.4 |
| 7.1 | 7.1.0.0 through 7.1.6.3 | AIX GPFS 7.1.6.4 Linux for z-series 7.1.6.4 Linux x86 7.1.6.4 |
Recommendation
- If the affected files have been not been deleted, use the "dsmmigundelete -expiring -recover" command to unexpire them on the TSM server. - Note: the dsmmigundelete operation will also recover the stubs which had been deleted from the GPFS after the SOBAR restore took place. Access Control Lists (ACLs) and extended attributes are not recovered by "dsmmigundelete".
- If the affected files have been deleted from the HSM storage pool on the TSM server and backup copies exist, use the command "dsmc restore -replace=yes -restoremigstate=no" to restore the files. - Note: The latter might require intermittent HSM migrations to avoid the GPFS becoming 100% full.
Who to call if you have questions about this problem
After reviewing this document, if you have additional questions, contact IBM Spectrum Protect technical support for further assistance. Be sure to say that you are calling about APAR IT17390.
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Document Information
Modified date:
25 September 2022
UID
swg21995449