RAID is not a backup!

This post describes the authors experience, almost losing his data on a RAID disk set. He also gives good details on why RAID is not a backup and how he rectified the situation. Remember: RAID is not a backup!

When working with corporate systems, a complete, reliable, and tested backup system is important. RAID does not protect you against many (or even most) disasters that could happen.

RAID is designed to protect against one thing: disk failure. It does not protect against user error, operator error, site destruction, and many more possibilities.

So how do I back things up? I must admit, I’ve improved my backup strategies of late. I currently have several tools that I use and would recommend to you:

  • SpiderOak. This is an online backup service which offers the first 2Gb backup free. They also maintain multiple version backup, so if you want a file from two versions back, it’ll still be there. This service is worth paying for, I’d say.
  • For my Mac, I’ve used PsyncX periodically (albeit not automated). It has come in handy more than once as my laptop died several times – I’ve one of those iBooks that was notorious for video hardware that failed annually (and Apple would fix for free, but never admitted fault). If you’ve a Mac, get an external drive and use PsyncX to save your home directory off. Also recommended: put your applications in your home directory, not the system directory: restoring your home directory will then be enough to get your applications back.
  • For UNIX, the similar alternative to PsyncX is rsync: again, get an external drive and save your home directory off to it regularly.
  • Also, come at it from the other direction: save your configuration by putting it into a cfengine or puppet setup and saving that as well. If the machine fails, running cfengine or puppet on startup will restore the system to its original state.
  • One other item – that may seem a bit unusual – is using Thinkfree Office. Thinkfree Office gives you a way to save documents locally and have them mirrored in the Internet cloud – and you can also manipulate your documents on the web as well. Of course, this is only entirely true for documents that Thinkfree Office can edit.

It would seem that cfengine v3 is now available for download – that will have to be a subject for a new article.

5 thoughts on “RAID is not a backup!”

  1. Great post. There’s a lot to think about. Reliable, off-site storage is the the only 100% sure solution. SpiderOak gives that and looks very good. But, alas, they don’t support Free/PC-BSD!

    Regarding the ThinkFree office, I notice it’s commercial. Why not use Google Doc.s to fill that role?

  2. Hello, I’m the CTO over at SpiderOak. Nice post. šŸ™‚ It’s astonishing the number of customers we talk to who are now in the market for a backup solution after learning the hard way that RAID != backup.

    As for *BSDs, we’re planning on extending support to those platforms in the future. Send an email to beta at if you’re interested. Most of SpiderOak is written in Python and should run whenever Python does. It’s mostly about testing and packaging to support additional platforms. We’re also hoping for a open source release in the not-distant future.

  3. I’d dare to say that ZFS with mirror (best across locations) and regular snapshots is for most stituations as good as having a real backup. Having parts of mirror in different locations protects you against site destruction, (here tapes won’t help you anyway, unless you do vaulting) snapshots will take care of accidental data deletion and ZFS self-healing will help in case of silent data corruption.

    If you like backup with versioning and rsync, you can have a combination of both: rdiff-backup.

  4. We have found that using BackupPC, an open source backup solution works very well. We use it to backup several hundred servers and 50+ workstations. These are both Linux and Windows servers and Linux, OS X and Windows servers.

    It can be found at

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