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I have been looking for about a week now at possible RAID options for the home file server I'm building. At first I was looking at RAID 5, but then read RAID 10 has faster read/writes. A few people wrote that if I went with a RAID 10 I should just go with a software RAID because there wouldn't be parity calculations.

So I am wondering, which would be better for a file/media server, RAID 5, or 10 (or is there a better alternative)? And would it be worth the 200-300 dollars to get a RAID card?

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Assuming the file server will be accessed over a LAN, then the performance bottleneck is likely to be the network, not the hard drives. In this case, I wouldn't opt for RAID 10 just on performance grounds.

A proper hardware RAID card is an expensive way to avoid the RAID 5 write hole. I believe that software RAID 5 - at least for mdadm - can avoid this problem using the resync feature; but power loss during a write and failure of one drive may still result in silent corruption.

Another alternative is RAID-Z in ZFS, which does not suffer from the write hole problem, yet it provides the same level of redundancy as RAID 5 (or RAID 6). There are several other benefits with ZFS. ZFS is natively supported in OpenSolaris, FreeBSD and FreeNAS.

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I was looking into ZFS, and it looks like you give up the ability to grow your array, for end-to-end data integrity, am I right? – Ben May 29 '11 at 22:34
Also note, I'm running on ubuntu (matters for ZFS apparently) – Ben May 29 '11 at 22:46
@mazzzzz Correct, at the moment it's not possible to add drives to an existing RAID-Z vdev. If that's an important factor, then off-the-shelf products like the Drobo FS or a Synology NAS might be better overall. – sblair May 29 '11 at 22:51
@mazzzzz Yes, ZFS with Linux is awkward. ZFS-FUSE is available, but not ideal because it's not integrated into the kernel. A couple of native ports/re-writes for Linux are in progress, but don't appear to be ready yet. For Linux, Btrfs might eventually supersede all these options - but again it's not ready now. – sblair May 29 '11 at 23:03
So my options are ZFS (a beta software I'm trusting my data to) or 300 dollar raid card. Talk about trying to pick the lesser of two evils. Anything specific to ubuntu (I have set up a software RAID 5, but it was a bit slow, and I'm worried if I do it with large amounts of data it will be easier for silent corruption to occur). – Ben May 30 '11 at 0:48

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