Veritas File System v5.0.1 Administrator's Guide for HP-UX 11i v3 (5900-0082, June 2010)
See “How a Storage Checkpoint works” on page 85.
Unlike a disk-based mirroring technology that requires a separate storage space,
Storage Checkpoints minimize the use of disk space by using a Storage Checkpoint
within the same free space available to the file system.
After you create a Storage Checkpoint of a mounted file system, you can also
continue to create, remove, and update files on the file system without affecting
the logical image of the Storage Checkpoint. A Storage Checkpoint preserves not
only the name space (directory hierarchy) of the file system, but also the user data
as it existed at the moment the file system image was captured.
You can use a Storage checkpoint in many ways. For example, you can use them
to:
■ Create a stable image of the file system that can be backed up to tape.
■ Provide a mounted, on-disk backup of the file system so that end users can
restore their own files in the event of accidental deletion. This is especially
useful in a home directory, engineering, or email environment.
■ Create a copy of an application's binaries before installing a patch to allow for
rollback in case of problems.
■ Create an on-disk backup of the file system in that can be used in addition to
a traditional tape-based backup to provide faster backup and restore
capabilities.
■ Test new software on a point-in-time image of the primary fileset without
jeopardizing the live data in the current primary fileset by mounting the
Storage Checkpoints as writable.
How Storage Checkpoints differ from snapshots
Storage Checkpoints differ from Veritas File System snapshots in the following
ways because they:
■ Allow write operations to the Storage Checkpoint itself.
■ Persist after a system reboot or failure.
■ Share the same pool of free space as the file system.
■ Maintain a relationship with other Storage Checkpoints by identifying changed
file blocks since the last Storage Checkpoint.
■ Can have multiple, read-only Storage Checkpoints that reduce I/O operations
and required storage space because the most recent Storage Checkpoint is the
only one that accumulates updates from the primary file system.
Storage Checkpoints
About Storage Checkpoints
84