[Lustre-discuss] Recommended segment size for MDS raid

[Alexander Oltu]

Hello,

I am trying to find information regarding optimal segment size for MDS
on RAID10 external array. Looking in documentation and searching
through mailinglist and google didn't help.

I found in Oracle DB documentation
(http://www.oracle.com/technology/deploy/availability/pdf/Engenio_LCS.pdf ,
p.11) that Oracle is using 1MB I/O size. That means that optimal
segment size for Oracle setup which has 4 data drives will be 1MB/4 =
256KB. But I am not sure what is the maximum I/O size for mdt.

Our setup MDS will be:
6 x 15K FC disks in RAID10 on Engenio 399x controller.

For mdt/mgs formatting we want to use -E stride= and stripe-width= ,
which we will calculate from RAID segment size.

Can somebody from Lustre guru advise optimal segment size for RAID 10
external array?

Thanks,
Alex.