From: Luke Lonergan <llonergan@greenplum.com>
To: Jim C. Nasby <jnasby@pervasive.com>
Cc: Mike Biamonte <mike@dbeat.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Huge Data sets, simple queries
Date: Tue, 31 Jan 2006 09:00:30 -0800
Message-ID: <C004D7AE.1B5A7%llonergan@greenplum.com> (raw)
In-Reply-To: <20060130202524.GB3920@pervasive.com>
Jim,
On 1/30/06 12:25 PM, "Jim C. Nasby" <jnasby@pervasive.com> wrote:
> Why divide by 2? A good raid controller should be able to send read
> requests to both drives out of the mirrored set to fully utilize the
> bandwidth. Of course, that probably won't come into play unless the OS
> decides that it's going to read-ahead fairly large chunks of the table
> at a time...
I've not seen one that does, nor would it work in the general case IMO. In
RAID1 writes are duplicated and reads come from one of the copies. You
could alternate read service requests to minimize rotational latency, but
you can't improve bandwidth.
- Luke
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To: pgsql-performance@postgresql.org
Cc: llonergan@greenplum.com, jnasby@pervasive.com, mike@dbeat.com
Subject: Re: Huge Data sets, simple queries
In-Reply-To: <C004D7AE.1B5A7%llonergan@greenplum.com>
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