Quoting Ross Walker <rswwal...@gmail.com>:
On Aug 15, 2009, at 4:46 PM, Mike La Spina <no-re...@opensolaris.org> wrote:
Hi,
The method you have chosen will not give you accurate read
performance data. The reads will be stored in cache and unless the
iostat call was invoked during a read cycle from disk you would not
see the actual io. Try installing and using bonnie++.
While true it will run from cache the fact that it's 16GB in size
should negate that given the system has 8GB of memory, as long as the
OP runs it twice for each and takes the second value.
But it still only measures asynchronous io performance. You'll need a
benchmark package to see synchronous io performance since dd doesn't
support the 'direct' flag.
-Ross
Thanks for the input everyone. I understand that I should be testing
with a benchmark program. But I'm confused a wee bit I guess because I
would imagine my asynchronous read performance to be much better than
48MB per second. Right/Wrong? Even if the read performance is not
accurate, it should still be ball park or greater than synchronous io.
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