On 8/19/2015 4:17 PM, Leon Fauster wrote:
Am 19.08.2015 um 10:24 schrieb John Hodrien <J.H.Hodrien@xxxxxxxxxxx>:
On Wed, 19 Aug 2015, Jatin Davey wrote:
Hi All
We use CentOS 6.6 for our application. I have profiled the application and find that we have a heavy requirement in terms of Disk writes. On an average when our application operates at a certain load i can observe that the disk writes / second is around 2 Mbps (Average).
Initial thought is, do you really care? 2Mbps is peanuts, so personally I'd
leave everything at the defaults. There's really no need to optimise
everything.
Obviously the exact type of writes is important (lots of small writes written
and flushed vs fewer big unsynced writes), so you'd want to poke it with
iostat to see what kind of writes you're talking about.
to address this we use (sysctl)
vm.dirty_expire_centisecs
vm.dirty_writeback_centisecs
furthermore check the fs alignment with
the underlying disk ...
--
LF
[Jatin]
These options deal with "caching" the writes. Correct me if i am wrong.
If it is indeed dealing with caching then i think it will not help
because the application workload generates a lot of data that is always
new. The application logic continously generates new data to be written
to disk.
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Thanks
Jatin
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