APPARATUS AND METHOD FOR FAST BACKUP AND RESTORE OR LARGE FILE SYSTEMS

APPAREIL ET METHODE DE SAUVEGARDE ET DE RECUPERATION RAPIDES DE FICHIERS VOLUMINEUX

Description

CA 02384020 2002-05-09
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02-05-01 CDN
Apparatus and Method for Fast Backup and Restore of Large File Systems
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is the first application filed for the present invention.
MICROFICHE APPENDIX
[0002] Not applicable.
FIELD OF INVENTION
[0003] This invention relates in general to the back up and restoration of
large computer file systems
BACKGROUND OF THE INVENTION
[0004] To be completed
SUMMARY OF THE INVENTION
[0005] To be completed
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] To be completed
DETAILED DESCRIPTION OF THE PREFERED EMBODIMENT
[0007] The proposed solution addresses shortcomings of using relatively
slow tape-based backup devices to create backup copies of large to medium size
RAID (Redundant Array of Inexpensive Disk) and non-RAID file system. The
proposed method and apparatus uses an inexpensive PC-based file server (a
backup server) to take a snap-ahot of the large RAID and non-RAID file system.
This snap-shot file system image is then backed-up to a slower backup media,
such as tape-based media. The snap-shot of the file system could be in a form
of
a full or incremental backup, or other campressed or uncompressed archive
file.
[0008] Using the backup server speeds up the initial stage of the backup
process of creating the snap-shot image, as the transfer rate at this stage of
the
backup is only limited by (network or other) connection between the RAID or
non-
RAID file system and the backup system. A dedicated 1000Base-T link between

CA 02384020 2002-05-09
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the file system and the backup system is preferable. An inexpensive crossed
CATS cable may be used to avoid use of a high-speed network hub/switch.
[0009] The snap-shot method also creates a more up-to-date image of the
file system that is being protected. Using tape-based storage devices often
causes uncertainty of backing up not the most recent data, as tape drives
provide
transfer rates two- or more orders of magnitude slower than hard disks in the
backup server with high-speed network connection and the backup process to a
tape can take a large amount of time to complete. In addition, the sheer size
of
RAID may create huge problerns when backing up or archiving it directly to a
tape device, as multiple media are needed. Since a typical backup process is
usually done during times of low file system activity, for example overnight,
it is
often required that the backup process completes without human assistance.
[0010] In the described invention, once the snap-shot of the file system is
placed on the backup server, ii: can be conventionally backed-up to a tape
media.
Since backups are usually performed every 24 hours, the tape backup of the
backup server can be performE~d on a more relaxed schedule, even during times
of high activity of the main RAID and non-RAID file system. The time allotted
to
complete the tape-based backup is now 24 hours minus the time necessary to
create the snap-shot image. The described process is such that, disk drives in
the backup server are not stressed, if used only, or mostly for the purpose of
storing the snap-shot image. This creates a very reliable intermediate storage
system. The disks of the backup server should also be automatically powered
down through BIOS and/or APIVI settings to reduce the stress and/or mounted
only when needed.
[0011] A process for restoring backed-up information uses a procedure
with the reversed order of steps taken during the backup operation. First, the
content of the backup media, for example tape media is restored to the backup
server. This initial restore may be performed over an extended period of time,
without disabling access to the file system. Next, the data, restored from
backup
media to the backup, is transferred at high speed to the file system.
Preferably, a
dedicated high speed connection between the backup server and the file system
is used, such as 1000Base-T network link. The restore operation is less
sensitive
to restore time in case of a tatal failure of the file system. However, during
a
typical restore operation only a damaged or lost fragment of the entire file
system
needs to be restored. In such ease, use of the invention minimizes the file
system
downtime and reduces the impact of the file system inaccessibility during the
restore operation.