From: Bram Van Steenlandt <bram@diomedia.be>
To: Graeme B. Bell <graeme.bell@nibio.no>
Cc: pgsql-performance@postgresql.org list <pgsql-performance@postgresql.org>
Subject: Re: large object write performance
Date: Thu, 08 Oct 2015 13:33:22 +0200
Message-ID: <56165482.7030109@diomedia.be> (raw)
In-Reply-To: <465F0A34-AE24-457A-8B3E-60440862D7EF@skogoglandskap.no>
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Op 08-10-15 om 13:21 schreef Graeme B. Bell:
>>> First the database was on a partition where compression was enabled, I changed it to an uncompressed one to see if it makes a difference thinking maybe the cpu couldn't handle the load.
>> It made little difference in my case.
>>
>> My regular gmirror partition seems faster:
>> dd bs=8k count=25600 if=/dev/zero of=./test
>> 25600+0 records in
>> 25600+0 records out
>> 209715200 bytes transferred in 1.513112 secs (138598612 bytes/sec)
>>
>> the zfs compressed partition also goes faster:
>> dd bs=8k count=25600 if=/dev/zero of=./test
>> 25600+0 records in
>> 25600+0 records out
>> 209715200 bytes transferred in 0.979065 secs (214199479 bytes/sec)
>> but this one didn't really go that fast in my test (maybe 10%)
>
> Please can you run iozone and look for low random write performance with small blocks? (4k)
> http://www.slashroot.in/linux-file-system-read-write-performance-testLike this ?
gmirror (iozone -s 4 -a /dev/mirror/gm0s1e) = 806376 (faster drives)
zfs uncompressed (iozone -s 4 -a /datapool/data) = 650136
zfs compressed (iozone -s 4 -a /datapool/data) = 676345
> Also please can you CC to the list with your replies to my on-list emails?
>
> Graeme Bell
>
>
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To: pgsql-performance@postgresql.org
Cc: bram@diomedia.be, graeme.bell@nibio.no
Subject: Re: large object write performance
In-Reply-To: <56165482.7030109@diomedia.be>
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