[Lustre-discuss] MDS - RAID0 or RAID1

[Carlos Santana]

On Tue, Jun 23, 2009 at 4:36 PM, Andreas Dilger<adilger at sun.com> wrote:
> On Jun 23, 2009  15:14 -0500, Carlos Santana wrote:
>> What RAID level should be used for MDS configuration? The manual seems
>> to suggest RAID1, however, the FAQ suggests RAID0 level.
>> http://manual.lustre.org/manual/LustreManual16_HTML/RAID.html#50401396_pgfId-1290495
>> http://wiki.lustre.org/index.php/Lustre_FAQ#What_is_the_typical_MDS_node_configuration.3F
>
> The MDT should always use RAID-1.  If you need more space than will fit
> on one disk, or you need more IOPS than can be handled by a single disk,
> then create sufficient RAID-1 pairs for your needs and then stripe them
> with RAID-0.  Having RAID-1 in pairs at the lower level minimizes the
> chance that multiple disk failures will cause data loss.
>
> I've clarified the FAQ in this regard.
>
>> Also, is it possible to add more OSTs as the requirement grows?
>
> Yes, adding new OSTs to an existing filesystem is a fairly common
> procedure.  Note if you are planning on expanding your filesystem
> in this way it makes sense to configure the MDT to have enough
> space/inodes for the OSTs that will be added in the future.
>
>> If yes, can additional resources be made part of RAID or can we
>> turn existing non-RAID system into a RAID system? Any insights?
>
> I'm not sure I understand this question.  OSTs should always use
> RAID to avoid data loss, though RAID-5 or RAID-6 is OK for OSTs.

My initial test setup does not have any RAID setup. I was planning to
further explore this into RAID setup. So I was curious abt it.
Thanks for the info..

-
CS.

>
> Cheers, Andreas
> --
> Andreas Dilger
> Sr. Staff Engineer, Lustre Group
> Sun Microsystems of Canada, Inc.
>
>