[Lustre-discuss] Disk array setup opinions

Indivar Nair indivar.nair at techterra.in
Mon Mar 11 08:30:15 PDT 2013

The best configuration to go for should be based on your file sizes, file
count and read / write patterns.
But as such you are right, Jerome.

*In general -*

The best RAID Configuration would be to create one that aligns with the 1MB
I/O size of Lustre.

Say you have 1 x MD3200 and 4 x MD1200 expansion arrays. That would give
you 60 Disks.
So the best option here would be to create 6  RAID6 Arrays of 10 Disks each.
In this case, you would end up having - 6 RAID6 Arrays = 6 LUNs  = 6 OSTs.

In each of the 10 Disk RAID6 Array, you would get 8 Data Disks and 2 Parity
Now if you divide 1MB (I/O Size) by 8 Data Disks, it gives you - *128KB* -
the segment / chunk size you should go for.
This config will align the I/O reads / writes, giving you the best
performance possible with the disk set.

Divide the 6 OSTs  among 2 OSS Nodes, and configure the nodes to act as
failover to each other.
Just ensure that each node has enough RAM to support 6 OSTs, in case one of
them fails.

Hope this helps.


Indivar Nair

On Mon, Mar 11, 2013 at 6:31 PM, Jerome, Ron <Ron.Jerome at ssc-spc.gc.ca>wrote:

> I am currently having a debate about the best way to carve up Dell
> MD3200's to be used as OST's in a Lustre file system and I invite this
> community to weigh in...
> I am of the opinion that it should be setup as multiple raid groups each
> having a single LUN, with each raid group representing an OST, while my
> colleague feels that it should be setup as a single raid group across the
> whole array with multiple LUNS, with each LUN representing an OST.
> Does anyone in this group have an opinion (one way or another)?
> Regards,
> Ron Jerome
> _______________________________________________
> Lustre-discuss mailing list
> Lustre-discuss at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-discuss
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