Hello Neil,

For the benchmarking purpose, I've configured array of ~30GB.
stripe_cache_size is 1024 (so 1M).

BTW, I'm using Windows copy (robocopy) utility to test perf and I
believe block size it uses is 32kB. But since everything gets written
thru VFS, I'm not sure how to change stripe_cache_size to get optimal
performance with this setup...

Thanks.

On Mon, Apr 11, 2011 at 7:51 PM, NeilBrown [off-list ref] wrote:

On Mon, 11 Apr 2011 18:57:34 -0700 Linux Raid Study
[off-list ref] wrote:

quoted

If I use --assume-clean in mdadm, I see performance is 10-15% lower as
compared to the case wherein this option is not specified. When I run
without --assume_clean, I wait until mdadm prints "recovery_done" and
then run IO benchmarks...

Is perf drop expected?

No.  And I cannot explain it.... unless the array is so tiny that it all fits
in the stripe cache (typically about 1Meg).

There really should be no difference.

NeilBrown

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