Version backup

In HSMS V12.0A  a new type of backup processing is introduced: version backup.

This provides the following features:

1. Backup and keep multiple file versions in the version backup archive for files cataloged in the respective pubset. The number of versions to keep is determined by the user in the file properties. 
   
2. A mechanism to ensure that a deleted file (possibly accidentally deleted) will be kept in the archive long enough in the previously backed up versions so that the user can take action to reconstruct the data.

Number of Backup Versions

The new file attribute NUM-OF-BACKUP-VERS (0..32) for the number of backup versions is introduced within BS2000 OSD V11.0B. This defines how many copies of a file are to be kept in the version backup archive at the same time.

NUM-OF-BACKUP-VERS = 0 means that the file will not participate in version backup. In the SM environment, the number of backup versions can also be controlled within management classes. The value in the management class predominates a deviating value in the catalog entry.

A new type of archive – the version backup archive – is introduced for the purpose of version backups.

There is one version backup archive per pubset where the desired number of file versions are saved - to always be sure that a consistent number of file versions are kept.

Thus, there are no user version backup archives. Version backups can be done only using system version backup archives. In both the SF and SM environments, they are defined Pubset-specifically and addressed by the symbolic name SYSVERSION. However, there is no global SYSVERSION archive for the SF environment.

The system version backup archive must be created as a public archive with write access (operand USER-ACCESS=*ALL-USERS/ACCESS=*WRITE) in order to enable nonprivileged users to save and restore data within this archive. Alternatively with ACCESS=*READ only the HSMS administrator may perform the save runs but the nonprivileged users are able to restore data from the archive.

The HSMS statement BACKUP-FILE-VERSIONS is used to save files in a version backup archive.

A user can specify the storage media from and to which the data is to be written.

Version Backup is not possible for:

• files on private disks
• FGGs
• temporary files
• catalog entries of tape files
• JVs

Figure: Version backup using BACKUP-FILE-VERSIONS

Version backup functionality available only as of BS2000 OSD/BC V11.0B, when a new file attribute NUMBER-OF-BACKUP-VERSIONS has been added, and in *HSMS-V10-COMPATIBLE mode. In an inhomogeneous BS2000/HSMS environment command will not be transferred to a master (backup server) running BS2000 < 11.0B or HSMS < 12.0A. The command request will be aborted on the host, which starts the request with an appropriate message.