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

Robert Olson olson at mcs.anl.gov
Mon Nov 19 11:25:32 PST 2007


>
> Well, you could start with the MDS on PPC, then try OSTs on PPC  
> without
> "-o mballoc,extents" mount options (you might need to pass
> "-o nomballoc,noextents" to cancel out the former default options).

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.

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.

Thanks,
--bob

PS  - interesting; readwrite test running now, driving the load avg  
on the MDT/OST node up to over 5. guessing a number of OST threads  
waiting on  disk..




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