Re: Tuning ext3 for large disk arrays

[Badari Pulavarty]

What kernel are you running ?  Does the kernel has ext3 "reservation"
support enabled ? Do you see performance problem with "read" tests also
? And also, does the write test writes to multiple files in the same
directory ? Or multiple threads writing to same file ?

Thanks,
Badari

On Tue, 2005-06-14 at 16:06, Peter Chubb wrote:
> Hi folks,
>    We've been doing a few scalability measurements on disk arrays.  We
> know how to tune xfs to give reasonable performance.  But I'm not sure
> how to tune ext3, and the default parameters give poor performance.
> 
> See http://scalability.gelato.org/DiskScalability/Results for the
> graphs.
> 
> iozone for 24 10k SATA disks spread across 3 3ware controllers gives a
> peak read throughput on XFS of around 1050M/sec; but ext3 conks out
> at around half that.  The maximum single threaded read performance we
> got was 450M/sec, and it's pretty constant from 12 through 24
> spindles.  We see no difference between setting -E stride=XX and
> leaving this parameter off.
> 
> The system uses 64k pages; we can set XFS up with 64k blocks; it may
> be that part of the problem is that ext3 can't use larger blocks.  We
> repeated the XFs measurements configuring the kernel and filesystem to
> use 4k pages/blocks, and although the throughput is lower than with
> the 64k page size, it's still significantly better than with ext3.
> Moreover, configuring XFS with 4k blocks, but using 64k pages gives
> results (not shown on the Wiki page) almost the same as the 64k
> pages/64k blocks.
> 
> Before going on and starting to look for bottlenecks, I'd like to be
> sure that ext3 is tuned appropriately.  mke2fs doesn't seem to have
> many appropriate tweaks, however...???
> 
> --
> Dr Peter Chubb  http://www.gelato.unsw.edu.au  peterc AT gelato.unsw.edu.au
> The technical we do immediately,  the political takes *forever*
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