Hello Peter,
Sunday, February 15, 2009, 12:54:40 PM, you wrote:
PT> On Sun, Feb 15, 2009 at 12:37 PM, Robert Milkowski <mi...@task.gda.pl>
wrote:
>> Hello Peter,
>>
>> Friday, February 13, 2009, 10:41:54 AM, you wrote:
>>
>> PT> I'm moving some data off an old machine to something reasonably new.
>> PT> Normally, the new machine performs better, but I have one case just now
>> PT> where the new system is terribly slow.
>>
>> PT> Old machine - V880 (Solaris 8) with SVM raid-5:
>>
>> PT> # ptime du -kds foo
>> PT> 15043722 foo
>>
>> PT> real 6.955
>> PT> user 0.964
>> PT> sys 5.492
>>
>> PT> And now the new machine - T5140 (latest Solaris 10) with ZFS striped
>> PT> atop a bunch of 2530 arrays:
>>
>> PT> # ptime du -kds foo
>> PT> 15343120 foo
>>
>> PT> real 2:55.210
>> PT> user 2.559
>> PT> sys 2:05.788
>>
>> PT> It's not just du; a find on that directory is similarly bad.
>>
>>
>> Maybe you have some extra tuning on the old server like increased
>> DNLC? I would check how many IOs (if any) you are doing during find
>> (not a 1st run of course)
>>
>> On the other hand your find/du will depend mostly on a single thread
>> performance and as you can see above you spending relative high
>> percentage on CPU and your T2+ will most probably deliver less single
>> thread performance than your V880.
PT> I know that. But 3 minutes against 6 seconds?
PT> The thing is, it's just this one set of data that's slow - I've not noticed
this
PT> performance falling off a cliff with all the other data that has been moved.
PT> (OK, there could be other datasets that have issues. But most of them don't
PT> and this one is obiously stuck in molasses.)
Well, if on old server you would have tuned DNLC so after a first pass
it caches all entires while on the new one you won't then there could
be a huge difference in timing. What's iostat -xn 1 output while doing
du/find on both servers (2nd run)? The only thing that worries me is
that on your new server you're still using more than 70% of CPU so it
doesn't necessarily look like you are waiting for IOs - or it could be
a combination of dnlc, single thread performance, ...
The dataset you are describing may also be hitting an issue with
running out of metaslabs which is using then a lot of CPU - I don't
believe it has been fixed yet. One workaround is to limit your
recordsize to 8K and then copy data again.
Anyway, without more details on IOs, DNLC and CPU utilization on both
servers it is really hard to say what is your problem.
--
Best regards,
Robert Milkowski
http://milek.blogspot.com
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
