[Lustre-discuss] Problems & partial success on PPC64 (XServe G5) Debian cluster

[Andreas Dilger]

On Nov 19, 2007  13:25 -0600, Robert Olson wrote:
> OK, early indications are good here. Started out with  MDT on PPC with OST 
> on intel, ran iozone up to 1M files and it finished without error and with 
> reasonable performance.

Can you please run "e2fsck -fn" (from a Lustre-patched e2fsprogs) on the
filesystems after your tests.

> Now running MDT + 1 OST on intel, 1 OST formatted with:
>
> mkfs.lustre --ost --fsname ppcfs --mgsnode=192.5.200.12 at tcp 
> --mountfsoptions=nomballoc,noextents /dev/sdc6
>
> on  PPC, iozone running in a directory set up to use the PPC OST with 
> setstripe (cool that you can do that).
>
> Job is still running, but no errors, and intermediate results look like 
> we're seeing good performance. iostat reporting good numbers on the disk on 
> the OST node.
>
> So what I am wondering now is what do I lose by turning of mballoc and 
> extents. My jobs don't do any sparse file writes or parallel writes to 
> files, mostly fairly small file access and the creation of some large 
> files.

The extents,mballoc options are primarily aimed at improving the performance
under high load by reducing CPU usage and getting better allocation.  if
you have mostly small files then the performance difference won't be huge.

Cheers, Andreas
--
Andreas Dilger
Sr. Software Engineer, Lustre Group
Sun Microsystems of Canada, Inc.