On 2010-02-02, at 09:46, Alexander Oltu wrote: > 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.
While Oracle recently bought Sun, I don't think this information is at all relevant. :-) > 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? Much of the MDT IO is in 4kB blocks, but whether that implies a 4kB RAID chunk size is a separate issue. Probably 64kB is the smallest practical size, given that smaller IOs to the disk don't go significantly faster. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
