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From: Evgeny Shishkin <itparanoia@gmail.com>
To: Craig James <cjames@emolecules.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Two identical systems, radically different performance
Date: Tue, 9 Oct 2012 02:08:29 +0400
Message-ID: <099BB618-4F80-4200-9564-4F06231D8D57@gmail.com> (raw)
In-Reply-To: <CAFwQ8rd1TTLh-BfMf-Uc2Vv_8GuP2uQqWAa6-FrtmJUhy3LVxQ@mail.gmail.com>
References: <CAFwQ8rcvw4mSoJ9q+ouONCeB9dg1T9gAUV5J27MpVZrehRHayQ@mail.gmail.com>
	<4CB0E3B6-CF1E-4B54-9900-E8356744F0AA@gmail.com>
	<CAFwQ8rd1TTLh-BfMf-Uc2Vv_8GuP2uQqWAa6-FrtmJUhy3LVxQ@mail.gmail.com>


On Oct 9, 2012, at 2:06 AM, Craig James <cjames@emolecules.com> wrote:

> 
> 
> On Mon, Oct 8, 2012 at 2:57 PM, Evgeny Shishkin <itparanoia@gmail.com> wrote:
> 
> On Oct 9, 2012, at 1:45 AM, Craig James <cjames@emolecules.com> wrote:
> 
>> I tested both the RAID10 data disk and the RAID1 xlog disk with bonnie++.  The xlog disks were almost identical in performance.  The RAID10 pg-data disks looked like this:
>> 
>> Old server:
>> Version  1.96       ------Sequential Output------ --Sequential Input- --Random-
>> Concurrency   1     -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
>> xenon        24064M   687  99 203098  26 81904  16  3889  96 403747  31 737.6  31
>> Latency             20512us     469ms     394ms   21402us     396ms     112ms
>> Version  1.96       ------Sequential Create------ --------Random Create--------
>> xenon               -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
>>               files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
>>                  16 15953  27 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
>> Latency             43291us     857us     519us    1588us      37us     178us
>> 1.96,1.96,xenon,1,1349726125,24064M,,687,99,203098,26,81904,16,3889,96,403747,31,737.6,31,16,,,,,15953,27,+++++,+++,+++++,++\
>> +,+++++,+++,+++++,+++,+++++,+++,20512us,469ms,394ms,21402us,396ms,112ms,43291us,857us,519us,1588us,37us,178us
>> 
>> 
>> New server:
>> Version  1.96       ------Sequential Output------ --Sequential Input- --Random-
>> Concurrency   1     -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
>> zinc         24064M   862  99 212143  54 96008  14  4921  99 279239  17 752.0  23
>> Latency             15613us     598ms     597ms    2764us     398ms     215ms
>> Version  1.96       ------Sequential Create------ --------Random Create--------
>> zinc                -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
>>               files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
>>                  16 20380  26 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
>> Latency               487us     627us     407us     972us      29us     262us
>> 1.96,1.96,zinc,1,1349722017,24064M,,862,99,212143,54,96008,14,4921,99,279239,17,752.0,23,16,,,,,20380,26,+++++,+++,+++++,+++\
>> ,+++++,+++,+++++,+++,+++++,+++,15613us,598ms,597ms,2764us,398ms,215ms,487us,627us,407us,972us,29us,262us
> 
> Sequential Input on the new one is 279MB/s, on the old 400MB/s. 
> 
> 
> But why? What have I overlooked?

blockdev --setra 32000 ?
Also you benchmarked volume for pgdata? Can you provide benchmarks for wal volume?
> 
> Thanks,
> Craig
> 

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