OT: Mirrored or RAID5

[Glenn Steen]

On 02/12/2007, UxBoD <uxbod at splatnix.net> wrote:
> Hi,
>
> I am just about to reinstall my home server with Centos5 and not sure the best configuration for the disks.  I have a 3Ware 9550SX Hardware RAID card with four 200GB drives in hot swap bays.  Currently I have two 200GB mirrored RAID sets, one for O/S and the other for data.  I am thinking about recreating the RAID set as one big RAID5 so that I can maximize the data area as only 10% is used in the O/S area.
>
> How does this approach sound ?  The server is a dual Opteron 250 with 6GB RAM.  Any help appreciated.
>
> Regards,
>
>From a performance perspective striping (without checksum) is fastest,
but since you have no "security" you will make the likelihood of a
failure much larger. R1 gives better performance than R5, for both
writes and reads. Combining striping (sometimes called R0) with
mirroring (called R1+0) will give you the best performance.
As a stopgap, you can have a large cache on your Raid controller, in
which case small I/O loads will never really depend on the disks, so
then an R5 can be acceptable.

Cheers
-- 
-- Glenn
email: glenn < dot > steen < at > gmail < dot > com
work: glenn < dot > steen < at > ap1 < dot > se