[Beowulf] Software RAID?

Bill Broadley bill at cse.ucdavis.edu
Wed Nov 21 16:34:44 PST 2007

Ekechi Nwokah wrote:
> Hi,
> Does anyone know of any software RAID solutions that come close to the

Yes, better even.

> performance of a commodity RAID card such as LSI/3ware/Areca for
> direct-attached drives?

Yes.  Of course there's a factor of 10 or more in the various cards
offered by those vendors.  Adaptec is another popular brand.

> With the availability multi-core chips and SSE instruction sets, it
> would seem to me that this is doable. Would be nice to not have to pay
> for those RAID cards if I don't have to. Just wondering if anything
> already exists.

Linux has software RAID built in.

Of course there are a zillion things you didn't mention.  How many drives did 
you want to use?  What kind? (SAS? SATA?)  If you want 16 drives often you get 
hardware RAID hardware even if you don't use it.  What config did you want? 
Raid-0? 1? 5? 6? Filesystem?

Oh, and how do you measure performance?  Bandwidth?  Seeks?  Transactions?
Transaction size?  Mostly read? write?

So while software RAID might end up being faster, you might end up buying
LSI, 3ware, areca, or adaptec cards anyways.  If you just need a few SATA
ports worth you may well have enough ports on the motherboard.

I'd also suggest checking the archives, fast file servers, filesystems, and
RAIDs have been discussed many times before.

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