Integrating Disk into Backup for Faster Restores Presented by W. Curtis Preston President The Storage Group, Inc.

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 off-site tapes Many people aren’t utilizing the tape drives properly, and are not getting all their backups done Also, many are not creating off-site copies Stand-alone tape drives must be swapped

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)

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 even 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.

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

Still not making off-site 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 off-site copies

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!

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

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

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 backup to disk Forever incremental w/o performance hit Some even eliminate redundant blocks across hosts

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

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 a fraction of the price! Backup large databases with no I/O overhead on server!

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

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

Why not do 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” on-site or off-site Tapes not susceptible to filesystem corruption

Issues… Staging process needs automation Increase ease of recovery 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 More products should support the creation of a “Synthetic Full,” creating a full from many incrementals Backup twinning should be able to go to disk and tape

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 off-site Many other features A directory of ATA Fibre & SCSI addressable arrays is available at: http://www.storagemountain.com Questions to curtis@thestoragegroup.com

Thank you! W. Curtis Preston President The Storage Group, Inc.