BACKUP/MASTER: Immediate Relief with Disk Backup

1. BACKUP/MASTER:Immediate Relief with Disk Backup Presented by W. Curtis Preston VP, Service Development GlassHouse Technologies, Inc

2. Tape backups are taking too long • High-speed tape drives in a library are the standard, but the cost of these units causes many people to cut corners elsewhere • The nature of tape drives also creates difficulty when creating offsite tapes • Many people aren’t utilizing the tape drives properly and are not getting all their backups done • Also, many are not creating offsite copies • Stand-alone tape drives must be swapped

3. Tape drives: The advantages • High-speed, low cost • Good archival solution. Allows multiple copies without significant cost. • Lots of new tape drives on the market: • 9940B (30/70 MB/s) • AIT-3 (15/30 MB/s) • LTO (15/30 MB/s) • Super DLT (11/22 MB/s)

4. Tape: The challenges • Tapes are now too fast! • Must use multiplexing to stream them during network backups • Must use higher multiplexing values than ever before, hurting restore performance more • Tape-to-tape copying takes time, and multiplexing increases that time – especially if you de-multiplex • Must perform regular full backups to reduce number of tapes required for restore • Incremental backups do not supply enough data to stream a tape drive

5. Tape: The challenges (2) • Cannot write to single tape drive from two shared servers simultaneously • Single tape can cause large restore to fail • You never know if a tape is good until you really need it

6. Still not making offsite copies • Assuming copy is same speed as backup, must buy at least twice as many drives to perform copies in one day • If copy is not same speed, must accept longer copy window or buy more tape drives • Additional drives cost a lot of money • Result: Many people still not making offsite copies

7. Solution: New backup media • Really inexpensive disk arrays • IDE/ATA-based • Addressable via Fibre Channel, SCSI, Firewire, NFS, or CIFS • JBOD and RAID configurations (Use their RAID controller or a software volume manager.) • As low as $5,000 per TB for off-shelf units, $2,000 for build-your-own units!

8. What to do with them? • Buy enough disk for two full backups and many, many incremental backups • Connect array to clients or backup servers via Fibre Channel & SANs, or GbE & NFS/CIFS

9. What to do with them? (2) • Back up to disk first using your backup software of choice • Duplicate disk backups to tape • Except in disaster, restores come from disk • Maybe place (another?) disk unit offsite and replicate to it

10. What to do with them? (3) • Most backup products do things that are not necessary when backing up to disk • Occasional full backups • Backing up redundant files • Incremental backups of entire files • New products designed to back up to disk • Forever incremental w/o performance hit • Some even eliminate redundant blocks across hosts

11. What to do with them? (4) • Replicate many clients to a central array, back up that array using backup software, and duplicate to tape for offsite copies • Allows you to use replication without the cost of traditional RAID arrays

12. What to do with them? (5) • Could also use software-based RAID to create additional mirror, and split mirror for backups • Gives you BCV functionality for ¼ the price! • Back up large databases with no I/O overhead on server!

13. Why would you do that? • Don’t require constant stream • No need to multiplex on most disk devices • Depending on implementation, multiplexed backups may still be faster on disk • If you did multiplex your disk backups, you could easily de-multiplex the tape copies with no performance penalty • NFS/CIFS devices can be used simultaneously by many clients, without needing to stream each device

14. Why would you do that? (2) • Incremental backups with little data will not hurt performance of other backups • Protected via monitored RAID -- the loss of a single disk would be monitored and repaired, while the RAID group continued to protect the data • Disk-to-tape copies are easier than tape-to-tape copies • Could perform infrequent full backups without increasing the chance of failure • Full backups can be performed less often, saving networks and CPU utilization

15. Why not back up everything to disk? • Archiving purpose of backups requires older backups to be available • Tapes still much cheaper, allowing for multiple, stable copies to be put on “the shelf” onsite or offsite • Tapes not susceptible to filesystem corruption

16. Issues… • Staging process needs automation • Need to automatically move data from disk to tape without removing from disk • Should allow you to leave backups on disk ALAP, and automate moving data to tape when necessary (policy-based, not just retention-based.) • Increase ease of recovery • Need to be able to import disk images • Creation of a “Synthetic Full” would be very nice • Backup twinning should be able to go to disk and tape

17. In Short • Doing backups to inexpensive disk first allows for: • Faster, easier backups – especially incremental backups • Easier creation of offsite tapes • Easier restores both on- and offsite • Many other features • A directory of ATA Fibre & SCSI addressable arrays is available at: http://www.storagemountain.com • Questions to cpreston@glasshouse.com