Apparent strange disk behaviour in 6.0
Julian Elischer
julian at elischer.org
Sat Jul 30 19:17:22 GMT 2005
Poul-Henning Kamp wrote:
> In message <42EB5687.2070400 at elischer.org>, Julian Elischer writes:
>
>>Poul-Henning Kamp wrote:
>>
>>>In message <42E88135.30603 at elischer.org>, Julian Elischer writes:
>>>
>>>Please use gstat and look at the service times instead of the
>>>busy percentage.
>>
>>The snapshot below is typical when doing tar from one drive to another..
>>(tar c -C /disk1 f- .|tar x -C /disk2 -f - )
>>
>>dT: 1.052 flag_I 1000000us sizeof 240 i -1
>> L(q) ops/s r/s kBps ms/r w/s kBps ms/w d/s kBps ms/d %busy Name
>> 0 405 405 1057 0.2 0 0 0.0 0 0 0.0 9.8 | ad0
>> 0 405 405 1057 0.3 0 0 0.0 0 0 0.0 11.0 | ad0s2
>> 0 866 3 46 0.4 863 8459 0.7 0 0 0.0 63.8 | da0
>> 25 866 3 46 0.5 863 8459 0.8 0 0 0.0 66.1 | da0s1
>> 0 405 405 1057 0.3 0 0 0.0 0 0 0.0 12.1 | ad0s2f
>> 195 866 3 46 0.5 863 8459 0.8 0 0 0.0 68.1 | da0s1d
>>
>>even though the process should be disk limitted neither of the disks is anywhere
>>near 100%.
>
>
> This looks like an awful lot of small files since you write 8 times as much data
> as you read ?
>
> Since the write service time (ms/w) is low, I pressume you have
> some hefty disk hardware (with cache ?)
>
> Presumably you're using softupdates ?
>
> I wouldn't be surprised if you were limited by system time rather than disk in
> this scenario ?
system is 87% idle
>
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