Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

262 VERITAS Volume Manager Administrator’s Guide
For databases, a suitable mechanism must additionally be used to ensure the
integrity of tablespace data when the volume snapshot is taken. The facility to
temporarily suspend file system I/O is provided by most modern database
software. For ordinary files in a file system, which may be open to a wide variety of
different applications, there may be no way to ensure the complete integrity of the
file data other than by shutting down the applications and temporarily unmounting
the file system. In many cases, it may only be important to ensure the integrity of
file data that is not in active use at the time that you take the snapshot.
Methods of creating volume snapshots are described in the following sections:
◆ “Creating Instant Snapshots” on page 275 describes how to use the vxsnap command
to create and administer full-sized and space-optimized instant snapshots.
◆ “Creating Traditional Third-Mirror Break-Off Snapshots” on page 299 describes how
to use the vxassist command to create and administer traditional third-mirror
snapshots.
For details of how to use volume snapshots to implement off-host online backup, see
“Configuring Off-Host Processing” on page 315.
Note Snapshot creation using the vxsnap command is the preferred mechanism for
implementing online and off-host point-in-time copy solutions in VxVM. Support
for traditional third-mirror snapshots that are created using the vxassist
command may be removed in a future release.
Most VxVM commands require superuser or equivalent privileges.
Full details of how to recover from failures of instant snapshot commands may be found
in the “Recovery from Failure of Instant Snapshot Operations’’ chapter of the VERITAS
Volume Manager Troubleshooting Guide.