CA2384020A1

CA2384020A1 - Apparatus and method for fast backup and restore or large file systems

Info

Publication number: CA2384020A1
Application number: CA 2384020
Authority: CA
Inventors: Jacek Misztal
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-05-09
Filing date: 2002-05-09
Publication date: 2003-11-09

Description

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 _2_ 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.