[mythtv-users] Software RAID5 faster than RAID10?

[John Drescher]

On Mon, Apr 13, 2009 at 3:50 PM, Ben Curtis <mythtv at nosolutions.com> wrote:
> Well, unless I'm doing something really wrong in my testing, I've just
> learned that my Software RAID5 is faster at reading and writing than my
> Software RAID10.  Please disprove this if at all possible, as I'm sure this
> will be useful information for anyone setting up a new filesystem for their
> video or system partitions.  Looks like I may be converting my RAID10 to a
> RAID5.  If there are other methodologies I should use to test, let me know
> and I'll be happy to post the results.
>

Software raid5 should be faster than raid 10 for a single file and
reading. Remember raid5 reading is the same as raid0 with n-1 disks.
raid 10 read speed for a single file is n/2. Where n is the number of
disks used. At writing raid5 should be faster for a single large file
as well. Its more difficult to calculate though and depends highly on
the stripe cache. I mean if the stripe cache is working optimally and
you have a large file the stripe will not need to be read before
written.

John