Software RAID 5 or something else?

Bruno Wolff III bruno at wolff.to
Fri Jan 23 18:53:07 UTC 2009


On Fri, Jan 23, 2009 at 12:39:44 -0500,
  aragonx at dcsnow.com wrote:

> 2) I want to increase my performance.  I have benchmarked my read and
> write performance to and from this server.  Using Samba, I seem to be able
> to get about 50Mb/sec reads and 40Mb/sec writes.  I am on a gig network
> and would like to be able to max out the cards (90Mb/sec is what I get at
> work).
> 
> So, the question is, what should I do?
> 
> 1)  Bite the bullet and get the hardware RAID controller.  Will this give
> me the performance I want?
> 
> 2)  Go with a software RAID 5.  Will I lose performance with this
> configuration?  If I use this but only get modest performance gains, that
> would be acceptable.

Software raid is not a big hit on modern cpus. The big advantage of good
hardware raid is that battery backed cache will speed up random writes.
This is very important for database performance. Bad hardware raid is
not going to help and will lock you into specific hardware. (E.g. if your
controller card dies, you'll probably need to buy exactly the same kind
as a replacement.)

> 
> 3)  Go with some other software RAID level.

With 5 drives you might consider raid 6.




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