On 04/25/2013 12:39 AM, James Harper wrote:
I'm doing some testing and wanted to see the effect of increasing journal speed, and the fastest way to do this seemed to be to put it on a ramdisk where latency should drop to near zero and I can see what other inefficiencies exist.
I created a tmpfs of sufficient size, copied journal on to that, and started the OSD. It core dumped pretty quickly which I assume is related to direct io not being supported. I turned off journal dio and the osd started okay but never recovered.
How should I do this? Is there another type of ramdisk I should use or other journal options I should specify?
(and yes I understand that losing ramdisk will lose the osd - I'm just doing testing)
I did the test by flushing the journal, stopping osd, mounting the
tmpfs and modifying the conf so that journal is stored on tmpfs and it
worked like that for me.
Although as my real drive were limited I didn't saw too much improvements.
Matthieu.
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