Disk staging is using
disks as an additional, temporary stage of
backup
In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is "back up", w ...
process before finally storing backup to
tape.
Backups stay on disk typically for a day or a week, before being copied to tape in a background process and deleted afterwards.
The process of disk staging is controlled by the same software that performs actual backups, which is different from
virtual tape library
A virtual tape library (VTL) is a data storage virtualization technology used typically for backup and recovery purposes. A VTL presents a storage component (usually hard disk storage) as tape libraries or tape drives for use with existing backup ...
where intermediate disk usage is hidden from main backup software. Both techniques are known as ''D2D2T'' (disk-to-disk-to-tape).
Restoring data
Data is restored from disk ''if possible''. But if the data exists only on tape it is restored directly (no backward-staging on restore).
Reasons
Reasons behind using D2D2T:
* increase performance of small, random-access restores: disk has much faster random access than tape
* increase overall backup/restore performance: although disk and a tape have similar streaming throughput, you can easily scale disk throughput by the means of
striping
In computer data storage, data striping is the technique of segmenting logically sequential data, such as a file, so that consecutive segments are stored on different physical storage devices.
Striping is useful when a processing device request ...
(and tape-striping is a much less established technique)
* increase utilization of
tape drive
A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and a long archival stability.
...
s: tape
shoe-shining effect
A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and a long archival stability.
...
is eliminated when staging (note that it may still happen on tape restores)
See also
*
Backup
In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is "back up", w ...
*
Virtual tape library
A virtual tape library (VTL) is a data storage virtualization technology used typically for backup and recovery purposes. A VTL presents a storage component (usually hard disk storage) as tape libraries or tape drives for use with existing backup ...
References
{{DEFAULTSORT:Disk Staging
Backup