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For Unix, there are several network file systems managed by the Computing Division, but we will broadly refer to their backups as NFS/GPFS/Lustre and AFS backups. NFS/GPFS/Lustre and AFS are backed up in different ways and have different backup schedules. However, there are a few underlying policies that were followed in setting up both backup systems. NOTE: not all file systems are backed up. Some Home directories are backed up, but most other directories are opt-in only. See below for more information.
For file systems that are backed up, NFS/GPFS/Lustre and AFS backups are performed automatically on a daily basis and should be viewed primarily as a way of recovering from hardware failures, not as an archival system. This means that the backups are not retained forever. Please see the retention period information below for each backup type.
NFS/GPFS/Lustre Backups and Recovering Your Own Files
Lustre home directories in the /sdf/home file system are backed up nightly. By default, we do not backup other NFS and , GPFS, or Lustre file systems unless requested to do so (opt-in). In those cases, backups run nightly and tapes must be provided by the groups who own the data. Please submit a backup request to unix-admin.
Those NFS/GPFS/Lustre file systems that are backed up are done so via IBM Tivoli Storage Manager (ITSM, or commonly just TSM) software. We currently support RHEL 6/7 and Centos 7 x86/x64 clients. Solaris SPARC/x86/x64 clients will be supported until existing hosts are retired.
Files are recovered from TSM by using the dsmj (GUI) or dsmc (command line) programs. If you backed up files from a Centos public machine, then you can also restore the file from that same host. Users may recover any file owned by their account using either interface, though the graphical interface may be easier to understand. See the How-to article "Restoring files using TSM" for instructions on restoring your files. To request the restoration of files you do not own or that were backed up directly from an NFS/GPFS/Lustre server (as opposed to the client you login to), send email to unix-admin. Include an explanation, the full path to the file, and from what point in time you need a restore.
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TSM maintains backup data for both active and inactive file versions. An active version of a file is the most recent backup copy of a file stored in TSM for a file that currently exists on a file server or workstation. An active version remains active on tape and exempt from tape deletion until: 1) replaced by a new backup version or 2) TSM detects, during an incremental backup, that the user has deleted the original file from a file server or workstation. An inactive version of a file is a copy of a backup file in TSM that either is not the most recent version, or the corresponding original file was deleted from the client file system.
Unless otherwise stated, the STANDARD retention policy is as follows:
- Up to 31 days copies of a particular file are kept on tape as long as the file exists on the client's file system.
- Only the most recently backed up version on tape is active. All other versions on tape are inactive but still recoverable.
- Once a file on tape goes inactive, it expires after 31 days and gets deleted off tape.
- If a file is deleted from a client's disk, several things happen during the next full incremental backup: 1) the active version of that file on tape will be marked inactive, 2) all inactive copies start expiring off tape as they reach 31 days of age, and 3) the last remaining inactive copy (which is also the most current backup copy) will be kept for 31 days, after which it expires too.
- Note that as long as a file remains on a client's disk, its latest backup copy will remain active on tape and not expire.
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AFS Backups and Recovering Your Own Files
Older home directories are located in the AFS file system and are backed up nightly, as are most (but not all) AFS group directories. AFS backups are provided by the native AFS backup systemTiBS software from Teradactyl. The unit of AFS file storage and backup is the volume. Typically, each user's home directory is a single volume. For the first level of backup, AFS TiBS creates a copy of each volume at midnight each night. This copy is called a "backup volume". You can find this backup volume from the .backup link in each home directory. If you have just deleted or damaged a file that existed at midnight the previous night, type "cd ~/.backup" to find a version of it from the previous day and copy it back into your home directory.
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AFS Backup Schedule and Retention Policy
The AFS backup is backups are a series of full and incremental backups, designed to provide complete coverage of recent changes, and sparser coverage going back in time. A level 0 backup is a full backup of the AFS file system. A level 1 backup is an incremental backup of all changes since the previous level 0 backup. A level 2 backup is an incremental backup of all changes since the previous level 1 backup. The schedule of AFS backups is as follows:
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