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I want to provide protection against data loss on my servers.

Typically, I'd use hardware RAID 1 or 5, but I've been reading up on ZFS.

Is it correct that ZFS itself provides RAID 1 or 5 like data protection WITHOUT needing a RAID controller card?

If so, I assume a single hard drive is not enough to provide data protection since if that drive fails, all data fails, so how many hard drives do I need to be running for ZFS to provide this protection?

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migrated from stackoverflow.com Jun 7 '12 at 6:14

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1 Answer 1

up vote 14 down vote accepted

Yes, ZFS doesn't need hardware raid and is actually better when used without it.

It is able to provide partial data protection even with a single device when configured to use ditto blocks but of course won't resist a full disk failure in that case.

You can use it in a mirror configuration (two devices or more) or a RAIDZ one (three devices or more) to survive failures. RAID-Z2 and RAID-Z3 provide 2 and 3 concurrent device failures protection.

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+1 It's highly recommend to not use a Hardware RAID controller with ZFS. –  Chris S Jun 7 '12 at 15:48
    
How well does that scale? Saying to a little small 4U case with 72 disc slots? –  TomTom Jun 7 '12 at 16:27
    
@TomTom That depends on how you organize your pool(s) which itself depends on your goals. –  jlliagre Jun 7 '12 at 22:14
    
@TomTom - also depends on how much RAM is in the system. ZFS is pretty memory hungry. Also be wary of heat if you have 72 disks in a 4U chassis. –  ghoti Jun 27 '12 at 12:31
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Hardly. Check SuperMicro - they offer those cases and they are perfectly fine heat wise ;) THis is not a hommade solution, it is pretty much an enterprise component. I currently use 22 discs for storage and they approach a too alrge fill factor. –  TomTom Jun 27 '12 at 12:35

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