From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Jeffrey W. Baker <jwbaker@acm.org>
Cc: Peter Darley <pdarley@kinesis-cem.com>
Cc: Pgsql-Performance <pgsql-performance@postgresql.org>
Subject: Re: Battery Backed Cache for RAID
Date: Wed, 14 Sep 2005 16:03:24 -0400
Message-ID: <20050914200324.GB26714@surnet.cl> (raw)
In-Reply-To: <1126722523.27650.6.camel@toonses.gghcwest.com>
References: <PDEOIIFFBIAABMGNJAGPAELFDOAA.pdarley@kinesis-cem.com>
<1126722523.27650.6.camel@toonses.gghcwest.com>
On Wed, Sep 14, 2005 at 11:28:43AM -0700, Jeffrey W. Baker wrote:
> On Wed, 2005-09-14 at 11:25 -0700, Peter Darley wrote:
> > I'm getting a new server for our database, and I have a quick question
> > about RAID controllers with a battery backed cache. I understand that the
> > cache will allow the cache to be written out if the power fails to the box,
> > which allows it to report a write as committed safely when it's not actually
> > committed.
>
> Actually the cache will just hold its contents while the power is out.
> When the power is restored, the RAID controller will complete the writes
> to disk. If the battery does not last through the outage, the data is
> lost.
Just curious: how long are the batteries supposed to last?
--
Alvaro Herrera -- Valdivia, Chile Architect, www.EnterpriseDB.com
Hi! I'm a .signature virus!
cp me into your .signature file to help me spread!
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: alvherre@alvh.no-ip.org, jwbaker@acm.org, pdarley@kinesis-cem.com
Subject: Re: Battery Backed Cache for RAID
In-Reply-To: <20050914200324.GB26714@surnet.cl>
* 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