Quoting Bob Friesenhahn <[email protected]>:
On Thu, 14 May 2009, [email protected] wrote:
I see alot of people use iozone, but I don't really understand why
some of the performance numbers exceed the maximum throughput in
theory for 12 SAS disks.
In order to effectively use iozone to measure "hardware" I/O you need
to use huge files which are at least several times larger than
available RAM. Otherwise you are measuring the effectiveness of the
system caching (e.g. ARC cache) and you will find that Solaris is very
effective at caching.
Thanks for that input.
So here is my iozone command:
iozone -R -a -z -b file.wks -g 16G -f testile
While that was running in a screen, I popped over to another screen
and ran iostat.
device r/s w/s kr/s kw/s wait actv svc_t %w %b tin tout
us sy wt id
fd0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 0 1182
0 3 0 97
sd0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd2 0.0 1524.8 0.0 195173.1 34.0 1.0 22.9 100 99
sd3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd10 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd11 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd12 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd13 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd14 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
I noticed alot of this where the pool members had no activity
according to iostat, but the ssd being used heavily. I don't really
understand, but can someone give me some insight into this?
Thanks
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