[Lustre-discuss] Disk array setup opinions

[Christopher J. Walker]

On 11/03/13 15:30, Indivar Nair wrote:
> 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 Disks.
> 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.
> 


http://content.dell.com/uk/en/enterprise/d/hpcc/cambridge-hpc-solution-centre

Has links to a couple of white papers with Dell MD3200s and MD1200s in a
failover configuration. They use 2*(MD3200 + 4*MD1200 +server) to give a
failover solution - which looks like exactly the setup you describe.

Chris


> Hope this helps.
> 
> Regards,
> 
> 
> Indivar Nair
> 
> 
> On Mon, Mar 11, 2013 at 6:31 PM, Jerome, Ron <Ron.Jerome at ssc-spc.gc.ca
> <mailto: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
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