From: Yeb Havinga <yebhavinga@gmail.com>
To: Greg Smith <greg@2ndquadrant.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Testing Sandforce SSD
Date: Sat, 24 Jul 2010 23:22:12 +0200
Message-ID: <4C4B5984.4010705@gmail.com> (raw)
In-Reply-To: <4C4B4512.2060007@gmail.com>
References: <4C4A9452.9070100@gmail.com>
<4C4B1F84.5030306@2ndquadrant.com>
<4C4B43DA.90201@gmail.com>
<4C4B4512.2060007@gmail.com>
Yeb Havinga wrote:
> Yeb Havinga wrote:
>> diskchecker: running 37 sec, 4.47% coverage of 500 MB (1468 writes;
>> 39/s)
>> Total errors: 0
>>
>> :-)
> OTOH, I now notice the 39 write /s .. If that means ~ 39 tps... bummer.
When playing with it a bit more, I couldn't get the test_file to be
created in the right place on the test system. It turns out I had the
diskchecker config switched and 39 write/s was the speed of the
not-rebooted system, sorry.
I did several diskchecker.pl tests this time with the testfile on the
SSD, none of the tests have returned an error :-)
Writes/s start low but quickly converge to a number in the range of 1200
to 1800. The writes diskchecker does are 16kB writes. Making this 4kB
writes does not increase writes/s. 32kB seems a little less, 64kB is
about two third of initial writes/s and 128kB is half.
So no BBU speeds here for writes, but still ~ factor 10 improvement of
iops for a rotating SATA disk.
regards,
Yeb Havinga
PS: hdparm showed write cache was on. I did tests with both ext2 and
xfs, where xfs tests I did with both barrier and nobarrier.
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: yebhavinga@gmail.com, greg@2ndquadrant.com
Subject: Re: Testing Sandforce SSD
In-Reply-To: <4C4B5984.4010705@gmail.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox