Friday, 18 September 2009

Backup Best Practices

If the data on your server was lost, what would you do?

At some point, everyone will lose data. It is often at this point you will realise how good your backup strategy is. There are several data loss scenarios to consider...

Hardware Failure
Hardware is becoming more and more resilient, but it will never be 100% perfect. Although better quality components cost more and reduce the risk of failure, failure can never be completely eliminated. Backing up your data will allow you to be prepared when it does happen. A common misconception is that backups are not required when a server has mirrored disks or RAID. This is not the case!

User Error
Users can often delete or overwrite important files accidentally. Sometimes they realise this immediately, other times the error is not detected until much later when the file is next needed. Having a backup which enables you to retrieve files from a long time ago will help in this situation.

Fire/Theft/Flooding
The end result of these can be the same as a hardware failure: an unusable box and no data. Did you know: In the UK, a home or business is more likely to flood, than have a fire? (source: Environment Agency). You probably have a burglar alarm and fire extinguishers, yet flooding is more likely than fire. No matter how good your hardware, it won’t withstand a fire and will almost certainly be affected should it flood.

Solutions
It may sound daunting, but a good backup plan is simple, requiring only a few factors to be taken into account. There is no perfect solution, rather a best-fit which balances the needs of the business or individual against the budget available.

Considerations...

Ensure Sufficient History

Say the only backup available to you is last night's copy. If an important file was deleted several days or weeks ago, you will have no backup containing that deleted file. Part of the process to decide a backup plan should include consideration of how far back your backups may need to go.

Offsite Storage
It is vital to have some form of offsite backup. Keeping all your tapes neatly on top of the server is no good. If a fire engulfs the server room, you're left with nothing. Having an offsite backup which is two years old is also little use in most circumstances. Fire safes do not necessarily guarantee that the tapes or devices stored in them will be usable after a fire. It is important as part of an offsite rotation routine, that there is always at least one tape offsite and that all the tapes are not in the same place at the same time (that could be when the fire strikes, destroying all hardware and backups)

Test Your Solution!
If you have a solution, do you know that it works? Does somebody check regularly to see that the backup is working? Have you tried to get data back so that you are happy that the solution works? Do you know which tape contains the data you need? Many people find out their backup hasn’t been working when a disaster happens.

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