Protecting data in a file system using the mmbackup command
The mmbackup command can be used to back up some or all of the files of a GPFS™ file system to Tivoli® Storage Manager (TSM) servers using the TSM Backup-Archive client. After files have been backed up, you can restore them using the interfaces provided by TSM.
The mmbackup command utilizes all the scalable, parallel processing capabilities of the mmapplypolicy command to scan the file system, evaluate the metadata of all the objects in the file system, and determine which files need to be sent to backup in TSM, as well which deleted files should be expired from TSM. Both backup and expiration take place when running mmbackup in the incremental backup mode.
The mmbackup command can interoperate with regular TSM commands for backup and expire operations. However if after using mmbackup, any TSM incremental or selective backup or expire commands are used, mmbackup needs to be informed of these activities. Use either the -q option or the --rebuild option in the next mmbackup command invocation to enable mmbackup to rebuild its shadow databases. (See mmbackup Examples in IBM Spectrum Scale: Administration and Programming Reference.)
These databases shadow the inventory of objects in TSM so that only new changes will be backed up in the next incremental mmbackup. Failing to do so will needlessly back up some files additional times. The shadow database can also become out of date if mmbackup fails due to certain TSM server problems that prevent mmbackup from properly updating its shadow database after a backup. In these cases it is also required to issue the next mmbackup command with either the -q option or the --rebuild options.
- A full backup of all files in the specified scope.
- An incremental backup of only those files that have changed or been deleted since the last backup. Files that have changed since the last backup are updated and files that have been deleted since the last backup are expired from the TSM server.
- Utilization of a fast scan technology for improved performance.
- The ability to perform the backup operation on a number of nodes in parallel.
- Multiple tuning parameters to allow more control over each backup.
- The ability to backup the read/write version of the file system or specific global snapshots.
- Storage of the files in the backup server under their GPFS root directory path independent of whether backing up from a global snapshot or the live file system.
- Handling of unlinked filesets to avoid inadvertent expiration
of files. Note: Avoid unlinking a fileset while running mmbackup. If a fileset is unlinked before mmbackup starts, it is handled; however, unlinking a fileset during the job could result in a failure to back up changed files as well as expiration of already backed up files from the unlinked fileset.
The mmbackup command supports backing up GPFS file system data to multiple Tivoli Storage Manager servers. The ability to partition file backups across multiple TSM servers is particularly useful for installations that have a large number of files. For information on setting up multiple TSM servers, see Tivoli Storage Manager requirements.
Unless otherwise specified, the mmbackup command backs up the current active version of the GPFS file system. If you want to create a backup of files at a specific point in time, first use the mmcrsnapshot command to create either a global snapshot or a fileset-level snapshot, and then specify that snapshot name for the mmbackup -S option. A global snapshot can be specified for either --scope filesystem or --scope inodespace. A fileset-level snapshot can only be specified with --scope inodespace.
If an unlinked fileset is detected, the mmbackup processing will issue an error message and exit. You can force the backup operation to proceed by specifying the mmbackup -f option. In this case, files that belong to unlinked filesets will not be backed up, but will be removed from the expire list.
If you have file systems that were backed up using the GPFS 3.2 or earlier version of the mmbackup command, you will not be able to take advantage of some of the new mmbackup features until a new full backup is performed. See File systems backed up using GPFS 3.2 or earlier versions of mmbackup.