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Re: postgresql 8.3 tps rate

From: Craig James <craig_james(at)emolecules(dot)com>
To:
Cc: Ibrahim Harrani <ibrahim(dot)harrani(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: postgresql 8.3 tps rate
Date: 2009-01-22 22:44:08
Message-ID: 4978F6B8.4050208@emolecules.com (view raw or flat)
Thread:
Lists: pgsql-performance
David Rees wrote:
> On Thu, Jan 22, 2009 at 1:27 PM, Ibrahim Harrani
> <ibrahim(dot)harrani(at)gmail(dot)com> wrote:
>> Version 1.93d       ------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
>> myserver 300M   391  97  9619   1  8537   2   673  99 +++++ +++  1196  16
>> Latency               211ms     388ms     325ms   27652us     722us    6720ms
>> Version 1.93d       ------Sequential Create------ --------Random Create--------
>> myserver    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
>>              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
>>                 16  9004  25 +++++ +++ +++++ +++  8246  20 +++++ +++ +++++ +++
>> Latency               592ms     208us     102us     673ms     179us     100us
> 
> You should be testing bonnie with a file size that is at least double
> the amount of memory in your machine - in this case, 4GB files, not
> 300MB files.
> 
>> When I compare my  bonnie++ result with the one at
>> http://www.westnet.com/~gsmith/content/postgresql/pg-disktesting.htm,
>> It seems that there is something wrong with the disks!?
> 
> Yes, your machine appears to be very slow.  You should be able to
> write in the order of 30-50MB/s+ and read in the order of 40-80MB/s+.
> Random IO should be in the 200 tps range for a 7200rpm SATA RAID1.

Have you tried the really basic speed test?

  time (dd if=/dev/zero of=bigfile bs=8192 count=1000000; sync)

  time dd if=bigfile of=/dev/null bs=8192

Divide 8.2GB by the times reported.  On a single 10K SATA drive, I get about 55MB/sec write and 61 MB/sec read.

If you can't get similar numbers, then something is wrong.

Craig

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Subject: Re: postgresql 8.3 tps rate
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