Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

Storage Checkpoint image is managed and available through the GUI, or the
Veritas Storage Foundation command line interface (CLI).
Veritas NetBackup also makes use of Storage Checkpoints to provide a very
efficient Oracle backup mechanism.
See the Veritas Storage Foundation for Oracle Graphical User Interface Guide.
A direct application of the Storage Checkpoint facility is Storage Rollback. Because
each Storage Checkpoint is a consistent, point-in-time image of a file system,
Storage Rollback is the restore facility for these on-disk backups. Storage Rollback
rolls back changed blocks contained in a Storage Checkpoint into the primary file
system for restoring the database faster.
For more information on Storage Checkpoints and Storage Rollback, see the Veritas
File System Administrator's Guide.
How Storage Checkpoints and Storage Rollback work
A Storage Checkpoint is a disk and I/O efficient snapshot technology for creating
a “clone” of a currently mounted file system (the primary file system). Like a
snapshot file system, a Storage Checkpoint appears as an exact image of the
snapped file system at the time the Storage Checkpoint was made. However, unlike
a snapshot file system that uses separate disk space, all Storage Checkpoints share
the same free space pool where the primary file system resides unless a Storage
Checkpoint allocation policy is assigned. A Storage Checkpoint can be mounted
as read-only or read-write, allowing access to the files as if it were a regular file
system. A Storage Checkpoint is created using the dbed_ckptcreate command
or the GUI.
Initially, a Storage Checkpoint contains no data—it contains only the inode list
and the block map of the primary fileset. This block map points to the actual data
on the primary file system. Because only the inode list and block map are needed
and no data is copied, creating a Storage Checkpoint takes only a few seconds and
very little space.
A Storage Checkpoint initially satisfies read requests by finding the data on the
primary file system, using its block map copy, and returning the data to the
requesting process. When a write operation changes a data block "n" in the primary
file system, the old data is first copied to the Storage Checkpoint, and then the
primary file system is updated with the new data. The Storage Checkpoint
maintains the exact view of the primary file system at the time the Storage
Checkpoint was taken. Subsequent writes to block "n" on the primary file system
do not result in additional copies to the Storage Checkpoint because the old data
only needs to be saved once. As data blocks are changed on the primary file system,
the Storage Checkpoint gradually fills with the original data copied from the
Using Storage Checkpoints and Storage Rollback
About Storage Checkpoints and Storage Rollback
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