Andreas Dilger wrote:
On Aug 19, 2009 13:55 +0200, Arne Wiebalck wrote:Brian J. Murrell wrote:On Wed, 2009-08-19 at 11:45 +0200, Arne Wiebalck wrote: Unless you are making lots and lots of small OSTs -- which is not usually beneficial anyway -- typically, you will run into resource limitations (memory, bus bandwidth, etc.) on an OSS before you hit a limit on the number of OSTs.I just thought I remembered there was something like 8 OSTs per OSS, but apparently I was wrong.Just how many OSTs are you considering, and how big will they be?My OSSs will have 10 OSTs with 1TB each.Is there a reason to do this instead of, say, two 5TB OSTs using MD RAID-0?
I thought a higher number of independent spindles was better. I should add that the 1TB OSTs are HW RAID-1s already.
Or for that matter one 8+2 8TB OST with MD RAID-6? That will give better space utilization if you have large files, otherwise you will have a lot of smaller chunks of free space on each OST that cannot be utilized well when the OSTs are nearly full. If you are looking at straight performance it may be that 10x 1TB OSTs is the fastest, since each one can be seeked independently. Reducing the journal size from the default 400MB is probably not harmful if you have correspondingly more OSTs.
OK, thanks for the hints. Cheers, Arne
smime.p7s
Description: S/MIME Cryptographic Signature
_______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
