Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

Note: Storage Checkpoints can only be used to restore from logical errors such as
human mistakes or software faults. You cannot use them to restore files after a
disk failure because all the data blocks are on the same physical device. Disk failure
requires restoration of a database from a backup copy of the database files kept
on a separate medium. Combining data redundancy (for example, disk mirroring)
with Storage Checkpoints is recommended for highly critical data to protect
against both physical media failure and logical errors.
Storage Checkpoints require space in the file systems where they are created, and
the space required grows over time as copies of changed file system blocks are
made. If a file system runs out of space, and there is no disk space into which the
file system and any underlying volume can expand, VxFS automatically removes
the oldest Storage Checkpoints if they were created with the removable attribute.
If available, it is recommended that you use the VxDBA utility to administer
Storage Checkpoints when they are applied to database applications. See the
Veritas Storage Foundation Database Administrator’s Guide for details.
Creating Storage Checkpoints
To create Storage Checkpoints, select 3 Storage Checkpoint Administration
> Create New Storage Checkpoints in the VxDBA utility. This can be done with
a database either online or offline.
Note: To create a Storage Checkpoint while the database is online, ARCHIVELOG
mode must be enabled in Oracle. During the creation of the Storage Checkpoint,
the tablespaces are placed in backup mode. Because it only takes a few seconds
to take a Storage Checkpoint, the extra redo logs generated while the tablespaces
are in online backup mode are very small. To optimize recovery, it is recommended
that you keep ARCHIVELOG mode enabled.
Warning: Changes to the structure of a database, such as the addition or removal
of datafiles, make Storage Rollback impossible when made after a Storage
Checkpoint is taken. A backup copy of the control file for the database is saved
under the /etc/vx/vxdba/ORACLE_SID/checkpoint_dir directory immediately
after a Storage Checkpoint is created. If necessary, you can use this file to assist
with database recovery. If possible, both an ASCII and binary copy of the control
file are made, with the binary version being compressed to conserve space. Use
extreme caution if you attempt to recover your database using these control files.
It is recommended that you remove old Storage Checkpoints and create new ones
whenever you restructure a database.
Database recovery
Creating Storage Checkpoints
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