From: Dave Cramer <pg@fastcrypt.com>
To: Gregory Stark <stark@enterprisedb.com>
Cc: postgresql performance list <pgsql-performance@postgresql.org>
Subject: Re: best use of an EMC SAN
Date: Wed, 11 Jul 2007 10:14:41 -0400
Message-ID: <0DA358AF-4CF3-4910-8E48-26403AE8C0AC@fastcrypt.com> (raw)
In-Reply-To: <877ip7avda.fsf@oxford.xeocode.com>
References: <D02C9DBC-0127-4B62-ABE3-93646B6A3F9F@fastcrypt.com>
<877ip7avda.fsf@oxford.xeocode.com>
On 11-Jul-07, at 10:05 AM, Gregory Stark wrote:
> "Dave Cramer" <pg@fastcrypt.com> writes:
>
>> Assuming we have 24 73G drives is it better to make one big
>> metalun and carve
>> it up and let the SAN manage the where everything is, or is it
>> better to
>> specify which spindles are where.
>
> This is quite a controversial question with proponents of both
> strategies.
>
> I would suggest having one RAID-1 array for the WAL and throw the
> rest of the
This is quite unexpected. Since the WAL is primarily all writes,
isn't a RAID 1 the slowest of all for writing ?
> drives at a single big array for the data files. That wastes space
> since the
> WAL isn't big but the benefit is big.
>
> If you have a battery backed cache you might not need even that.
> Just throwing
> them all into a big raid might work just as well.
Any ideas on how to test this before we install the database ?
>
> --
> Gregory Stark
> EnterpriseDB http://www.enterprisedb.com
>
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To: pgsql-performance@postgresql.org
Cc: pg@fastcrypt.com, stark@enterprisedb.com
Subject: Re: best use of an EMC SAN
In-Reply-To: <0DA358AF-4CF3-4910-8E48-26403AE8C0AC@fastcrypt.com>
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