Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

59Understanding Veritas Volume Manager
Volume snapshots
depends on dirty region logs, redo log volumes should be configured as mirrored volumes
with sequential DRL.
For additional information, see “Sequential DRL” on page 57.
Volume snapshots
Veritas Volume Manager provides the capability for taking an image of a volume at a
given point in time. Such an image is referred to as a volume snapshot. Such snapshots
should not be confused with file system snapshots, which are point-in-time images of a
Veritas File System.
Figure 1-31 illustrates how a snapshot volume represents a copy of an original volume at a
given point in time. Even though the contents of the original volume can change, the
snapshot volume can be used to preserve the contents of the original volume as they
existed at an earlier time.
The snapshot volume provides a stable and independent base for making backups of the
contents of the original volume, or for other applications such as decision support. In the
figure, the contents of the snapshot volume are eventually resynchronized with the
original volume at a later point in time.
Another possibility is to use the snapshot volume to restore the contents of the original
volume. This may be useful if the contents of the original volume have become corrupted
in some way.
Note: If you choose to write to the snapshot volume, it may no longer be suitable for use in
restoring the contents of the original volume.