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Last Modified: Friday, 27-Mar-2009 14:06:50 EDT

CSB Filesystems -- Data Backup and Recovery


All non-temporary CSB filesystems are protected by multiple safeguards against user error or system failure. Seven days' worth of snapshots of all file systems are kept on line; permanent archives are made every 4-6 months. However, it is possible to defeat these efforts, and files can be permanently lost. Users should understand the limitations of the measures offered by the CSB, and take their own measures to protect essential data.

How CSB filesystems are protected

At present, /srv/frames is the only filesystems designated for temporary storage. Files on temporary storage are not protected in any way against mechanical or human failure. All other filesystems are subject to the following safeguards.

RAID storage

All non-temporary CSB filesystems are stored on RAID hardware. This means that if a single disk drive fails, no data are lost. The redundant data are rebuilt onto a spare drive, and the defective drive is replaced.

Daily snapshots

Early every morning, a complete snapshot is taken of all non-temporary CSB filesystems. The snapshot is stored on a server and RAID system completely independent of the primary system. In the event of catastrophic failure of the primary system, files can be recovered except for those modified since the morning's backup.

Snapshots will be retained for 7 days (but see caveats below). If you delete or modify a file, and later want to recover the original contents, you can retrieve it from the online snapshot.


Every 4-6 months, we create a "permanent" archive of all CSB non-temporary filesystems. Before September 2006, these archives were made on magnetic tape. Beginning with that date, we are using DVDs.

Tape Backup

Prior to September, 2006, a full backup of CSB filesystems was made roughly every three months. Incremental backups were made roughly every 10 days. The backups were made to tapes, which were re-used in rotation. Recovery of lost files was time consuming, requiring searching through various full and incremental backup tapes. This sytem has now been discontinued.

Data Recovery

The staff will assist in any requests for data recovery. The 7-day daily snapshot should allow for recovery of active files which are lost due to error or system failure. Most files of enduring importance will be on the filesystem long enough to be backed up on at lest oneof the 6-monthly archives.


Return to Disk use and Filesystems

Last Modified: Friday, 27-Mar-2009 14:06:50 EDT

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