Re: H800 + md1200 Performance problem

Yes, setting is the same in both machines.

The results of bonnie++ running without arguments are:

Version 1.96 ------Sequential Output------ --Sequential Input-
--Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec
%CP
cltbbdd01 126G 94 99 202873 99 208327 95 1639 91 819392 88
2131 139
Latency 88144us 228ms 338ms 171ms 147ms
20325us
------Sequential Create------ --------Random
Create--------
-Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files:max:min /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec
%CP
cltbbdd01 16 8063 26 +++++ +++ 27361 96 31437 96 +++++ +++ +++++
+++
Latency 7850us 2290us 2310us 530us 11us
522us

With DD, one core of CPU put at 100% and results are about 100-170 MBps,
that I thing is bad result for this HW:

dd if=/dev/zero of=/vol02/bonnie/DD bs=8M count=100
100+0 records in
100+0 records out
838860800 bytes (839 MB) copied, 8,1822 s, 103 MB/s

dd if=/dev/zero of=/vol02/bonnie/DD bs=8M count=1000 conv=fdatasync
1000+0 records in
1000+0 records out
8388608000 bytes (8,4 GB) copied, 50,8388 s, 165 MB/s

dd if=/dev/zero of=/vol02/bonnie/DD bs=1M count=1024 conv=fdatasync
1024+0 records in
1024+0 records out
1073741824 bytes (1,1 GB) copied, 7,39628 s, 145 MB/s

When monitor I/O activity with iostat, during dd, I have noticed that, if
the test takes 10 second, the disk have activity only during last 3 or 4
seconds and iostat report about 250-350MBps. Is it normal?

I set read ahead to different values, but the results don't differ
substantially...

Thanks!

El 3 de abril de 2012 15:21, Tomas Vondra <tv(at)fuzzy(dot)cz> escribió:

> On 3.4.2012 14:59, Cesar Martin wrote:
> > Hi Mike,
> > Thank you for your fast response.
> >
> > blockdev --getra /dev/sdc
> > 256
>
> That's way too low. Is this setting the same on both machines?
>
> Anyway, set it to 4096, 8192 or even 16384 and check the difference.
>
> BTW explain analyze is nice, but it's only half the info, especially
> when the issue is outside PostgreSQL (hw, OS, ...). Please, provide
> samples from iostat / vmstat or tools like that.
>
> Tomas
>
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--
César Martín Pérez
cmartinp(at)gmail(dot)com