From: Yeb Havinga <yebhavinga@gmail.com>
To: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
Cc: pgsql-performance@postgresql.org
Subject: Re: SSD and RAID
Date: Wed, 07 Mar 2012 10:45:09 +0100
Message-ID: <4F572E25.1000307@gmail.com> (raw)
In-Reply-To: <4F56ADA5.4040902@catalyst.net.nz>
References: <4F554025.9040101@catalyst.net.nz>
<4F55C802.8040401@gmail.com>
<4F56ADA5.4040902@catalyst.net.nz>
On 2012-03-07 01:36, Mark Kirkwood wrote:
> On 06/03/12 21:17, Yeb Havinga wrote:
>>
>>
>> One thing to note is that linux software raid with md doesn't support
>> discard, which might shorten the drive's expected lifetime. To get
>> some numbers I tested the raid 1 of ssd's setup for mediawear under a
>> PostgreSQL load earlier, see
>> http://archives.postgresql.org/pgsql-general/2011-11/msg00141.php
>>
>>
>
> Right, which is a bit of a pain - we are considering either formatting
> the drive with less capacity and using md RAID 1 or else doing the
> mirror in LVM to enable a working discard/trim.
When I measured the write durability without discard on the enterprise
disks, I got numbers that in normal production use would outlive the
lifetime of the servers. It would be interesting to see durability
numbers for the desktop SSDs, even when partitioned to a part of the disk.
regards,
Yeb Havinga
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To: pgsql-performance@postgresql.org
Cc: yebhavinga@gmail.com, mark.kirkwood@catalyst.net.nz
Subject: Re: SSD and RAID
In-Reply-To: <4F572E25.1000307@gmail.com>
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