Performing prerequisite tasks before creating an image backup

The following items are the image backup considerations.

• To perform an offline or online image backup you must have administrative authority on the system.
• You do not need more than one drive to perform an image backup.
• Ensure that no other application is using the volume when you run a static image backup. To ensure a consistent image during backup processing, if a file space is detected on the volume the client unmounts and remounts the volume as read only, so that no other applications can write to it. If the volume is in use when the client attempts to unmount, the backup fails. If the client cannot unmount and remount the volume as read only because it is in use, and snapshot image backup is not available, you can use the dynamicimage option to force the client to perform an image backup without unmounting and remounting the volume in read-only mode. Set the dynamicimage option in an include.image statement or from the command line. The backup can be corrupted if applications write to the volume while the backup is in progress. This can be corrected by running fsck after a restore to fix any corrupted blocks.

  If no file system is detected on the volume being backed up, ensure that all applications writing to the volumes are quiesced. The backup-archive client uses the file system table and mount table to detect the supported file systems.

  Do not include system files in an image backup because file systems being actively used cannot be unmounted.

  For AIX® and Linux only: If you perform an image backup of a mounted file system which is mounted to another mount point and specified in the file system table, then after completing the image backup, all mount options for this file system, except read or write state, is lost.

  Important: If a mounted file system has nested mount points, unmount them before attempting a backup. Otherwise, the client is unable to unmount the volume. The file system is rendered busy if it contains any mounts.

• Ensure that no other application is using the volume when you run an offline image backup. To ensure a consistent image during backup processing, the client locks the volume, so that no other applications can write to it. If the volume is in use when the client attempts to lock the volume, the backup fails. If the client cannot lock a volume because it is in use, you can perform an online image backup.
• Use the include.image option to assign a management class to the volume image. If you do not assign a management class, the default management class is used for the image.
  Note: If the snapshotproviderimage option is set to none, then the copy serialization parameters set by the management class is used.
• You can exclude a volume from image backup using the exclude.image option.
• You must use the mount point for the file system volume on which you want to perform an image backup. The client will not back up a file system volume without the use of a mount point. Back up file systems using the mounted name. For example, if /dev/lv01 is formatted as a file system mounted on /home, enter this command to perform an image backup of this volume:

  dsmc backup image /home

  Back up raw volumes using the device name. For example, if /dev/lv02 is a raw volume, enter this command to perform an image backup of this volume:

  dsmc  backup image /dev/lv02 

  If you back up a raw volume which is formatted as a file system, ensure that the file system is not mounted and does not have an entry in /etc/filesystems.

• You must use the mount point or drive letter for the volume on which you want to perform an image backup. The client will not back up a volume without the use of a drive letter or mount point.
• Do not include the system drive in an image backup because the client cannot have an exclusive lock of the system drive during the restore and the system drive image cannot be restored to the same location. Image backup does not guarantee consistency of system objects, such as the Active Directory. System objects can be spread out across multiple volumes, and should be backed up using the corresponding backup commands. Because you cannot restore an image backup to the volume from which the client is currently running (or any volume for which an exclusive lock cannot be obtained) you should install your client program on the system drive.
  Note: When using WinPE, an image restore of the system drive is possible. For more information, see Tivoli® Storage Manager Recovery Techniques Using Windows Preinstallation Environment (Windows PE).
• If bad disk sectors are detected on the source drive during a LAN-free or LAN-based image backup, data corruption can occur. In this case, bad sectors are skipped when sending image data to the Tivoli Storage Manager server. If bad disk sectors are detected during the image backup, a warning message is issued after the image backup completes.