22 Feb
2012
22 Feb
'12
10:26 a.m.
Hello,
On Wed, Feb 22, 2012 at 04:47:24AM +0000, Andy Smith wrote:
At the moment I am running a reinitialise on the RAID
array which is
going to take a couple of hours. Once that completes, if it hasn't
improved matters then I will be rebooting the node again.
Literally just a couple of minutes after typing the above email, I
decided that changing IO scheduler would squeeze a little more IOPS
out of it and so would be a good thing to do while waiting for the
initialise to complete.
Normally all BitFolk nodes run with 'cfq' as IO scheduler.
3ware recommends 'deadline' instead, but in previous testing I'd
found that 'cfq' was only slightly worse than 'deadline'. Since
'cfq' allows use of the 'ionice' command for crude disk IO quality
of service adjustments, I go with 'cfq' normally.
Well, to my vast confusion, as soon as it was switched to 'deadline'
all problems went away. Instead of it making for a very slight
benefit as expected, it has completely returned performance to
normal levels.
Lovely as this is, I do not like mysteries, so will need to continue
to investigate. However I don't now predict needing to do a reboot
or anything else drastic.
I disabled a few IO-intensive things in the early hours of the
morning to try to make life more bearable, and I'm now going to
re-enable those things.
Thanks again for your patience.
Cheers,
Andy
--
http://bitfolk.com/ -- No-nonsense VPS hosting
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