This topic lists some items to consider before you perform
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, Tivoli® Storage Manager 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. Tivoli Storage Manager 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. Tivoli Storage Manager 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. See Tivoli Storage Manager Recovery
Techniques Using Windows Preinstallation
Environment (Windows PE) for
more information.
- 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.