Veritas File System (VxFS) provides a Storage Checkpoint feature that quickly creates a persistent image of a file system at an exact point in time. Storage Checkpoints significantly reduce I/O overhead by identifying and maintaining only the file system blocks that have changed since the last Storage Checkpoint or backup via a copy-on-write technique.
Storage Checkpoints provide:
Persistence through reboots and crashes.
The ability for data to be immediately writeable by preserving the file system metadata, the directory hierarchy, and user data.
Storage Checkpoints are actually data objects that are managed and controlled by the file system. You can create, remove, and rename Storage Checkpoints because they are data objects with associated names.
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.