IBM Tivoli Storage Manager for UNIX and Linux Backup-Archive ...

You must be a root user to perform this task, and image backup does not apply toMac OS X.An image backup provides the following benefits:v Backs up file systems containing a large number of files faster than a full filesystem incremental back up.v Improves the speed with which Tivoli Storage Manager restores file systemscontaining many small files.v Conserves resources on the server during backups since only one entry isrequired for the image.v Provides a point-in-time picture of your logical volume, which might be useful ifyour enterprise needs to recall that information.v Restores a corrupt file system or raw logical volume. Data is restored to thesame state it was when the last logical volume backup was performed.The traditional static image backup prevents write access to the volume by othersystem applications during the operation. Use the dynamicimage option to back upthe volume as is without remounting it read-only. Corruption of the backup canoccur if applications continue to write to the volume while the backup is inprogress, which can result in inconsistent data and data loss after the restore. Thisoption overrides the copy serialization value in the management class to performan image backup. After restoring an image backup taken with the dynamicimageoption, always run the fsck utility.To restore an image backup of a volume, the Tivoli Storage Manager client must beable to obtain an exclusive lock on the volume being restored.Restriction: Tivoli Storage Manager dynamic image backups should not be usedfor file systems, because the file system’s internal design could provide inconsistentdata even when there is no write activity. Dynamic image backup could result in afuzzy image, and is not guaranteed to be valid or complete when restored.If the Tivoli Storage Manager client fails to mount the file system after restoring animage, you can run fsck. However, running fsck can affect the integrity of largeamounts of data. Dynamic image backup is not recommended for AIX JFS2 filesystems, so the Tivoli Storage Manager client does not allow dynamic imagebackup for AIX JFS2 file systems. If you specify dynamicimage=yes for a JFS2 filesystem, the Tivoli Storage Manager client will perform a snapshot-based imagebackup. If the snapshot cannot be created for some reason, the Tivoli StorageManager client will instead perform a static image backup.Important: To prevent data loss, avoid using dynamicimage, and ensure that thereis no write activity on the volume while the backup is in progress.For AIX JFS2 file systems, the amount of data backed up to the Tivoli StorageManager server during static or snapshot image backup will be reduced bybacking up only those blocks used by the file system or smaller than theimagegapsize option. This method of backing up your data will improve theperformance of image backup. Refer to “Imagegapsize” on page 328 for moreinformation.For AIX clients only: By default, Tivoli Storage Manager performs an onlinesnapshot image backup of JFS2 file systems, during which the volume is availableto other system applications.138 IBM Tivoli Storage Manager for UNIX and Linux Backup-Archive Clients Version 6.1: Installation and User’s Guide