[CentOS] Benchmark Disk IO
Jerry Franz
jfranz at freerun.com
Wed May 19 13:19:27 UTC 2010
On 05/19/2010 06:14 AM, John Doe wrote:
> From: Matt Keating<keatster at gmail.com>
>
>>> I don't usually use iozone (I usually use bonnie++) so take this with
>>> a grain of salt, but those speed look suspiciously like cache speeds.
>>> Bump the size (-s parameter) up to twice your real RAM size.
>>>
>> Will give that a try - 16gb file incoming
>>
> Or maybe do a:
> sync; echo 3> /proc/sys/vm/drop_caches
> between the 2 tests...?
>
It wouldn't help. The problem is the tests were using file sizes small
enough to easily fit completely into the system caches. So you end up
benchmarking the performance of the I/O system caches - not the drives
themselves.
--
Benjamin Franz
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