RAID Performance Questions

Jeff Mohler at
Thu Jan 25 21:50:54 UTC 2007

How about one large raid, and two partitions to serve each purpose?

Being so limited in HW, youre either going to take a _huuuuuge_
performance hit with only 2 disks per raid (unless Raid0), or an
availability hit with everything on one RAID set.

But..considering the costs of adding RAID to a server..take a peek
here for a high(er) perfomance RAID solution..if Fbsd had an iscsi
layer like linux has had for...5yrs or so..this would be a slam dunk
as you can still serve it as block data.

If that cant help you, it might help the next guy with only a few K's
to spend on large disks and raid controllers.

On 1/25/07, Milo Hyson <milo at> wrote:
> On Jan 25, 2007, at 12:15, Chuck Swiger wrote:
> > Still, you also ought to consider that a 3-disk RAID-5
> > configuration is very much not ideal from either an efficiency or
> > performance standpoint-- you want more like 5 or 6 drives being
> > used, in which case your performance numbers ought to increase
> > some.  This is also somewhat true of the 4-disk RAID-10 config;
> > using 6 or all 8 drives would likely improve performance compared
> > with striping against only two disks.
> Unfortunately, I'm a bit limited in terms of equipment and
> application requirements. For starters, the app specs currently call
> for two arrays: one for general file-serving and databases, and the
> other for backups. Due to limited hardware I'm to run both on the
> same controller. Far from ideal, I know, but it's what I have.
> Second, I need to keep at least one drive as a hot-spare. Thus, I
> have seven drives that I somehow need to partition into two groups
> and maximize performance without sacrificing reliability. Lastly, the
> RAID controller does not permit more than two drives in a RAID-1 set.
> Any suggestions?
> --
> Milo Hyson
> CyberLife Labs
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