On Thu, Feb 25, 2010 at 1:38 PM, Daniel Maher <dma+gluster@xxxxxxxxx> wrote:
Mostly reads are being served from io-cache?
Raghavendra G wrote:Some of the files that are generated during the test are under 128M, and some are much larger - effectively, the test deals with larger and larger sets of data as it runs its course.
Hi Daniel,
Can you decrease the cache size in io-cache (say to 128MB)? If the files being served are bigger than this size, you can as well remove io-cache from configuration. Do let us know if this solves your issue.
At your suggestion, i changed the io-cache size from the default setting (as generated by the configurator) to 128M, and re-ran the test. The results are now much more consistent with what would be expected :
real 21m31.019s
real 21m30.932s
real 21m28.965s
real 21m26.095s
real 21m26.388s
real 21m29.377s
real 21m32.180s
real 21m26.600s
real 21m28.354s
(cut for brevity)
However, at two points during the multi-day test run, something strange happened. The time to completion dropped _dramatically_, and stayed there for numerous iterations, before jumping back up again :
Mostly reads are being served from io-cache?
real 21m27.806s
real 21m45.434s
real 14m41.468s
real 12m41.172s
real 12m39.779s
real 12m34.595s
real 12m42.223s
real 12m41.111s
(repeat 30 iterations)
real 12m40.185s
real 12m40.517s
real 13m25.394s
real 21m26.375s
real 21m28.476s
I am forced to assume that something else on either the client or the server nodes caused this behaviour, but i cannot imagine what. The nodes, frankly, aren't doing anything else. Very strange.
I am going to remove the io-cache entirely and see what, if any, effect that has.
--
Daniel Maher <dma+gluster AT witbe DOT net>
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--
Raghavendra G
