From: Gregory Stark <stark@enterprisedb.com>
To: Scott Carey <scott@richrelevance.com>
Cc: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Thomas Finneid <tfinneid@student.matnat.uio.no>
Cc: Craig Ringer <craig@postnewspapers.com.au>
Cc: pgsql-performance@postgresql.org
Subject: Re: slow update of index during insert/copy
Date: Mon, 01 Sep 2008 20:41:48 +0100
Message-ID: <873akjodqb.fsf@oxford.xeocode.com> (raw)
In-Reply-To: <a1ec7d000809011146x456b942eof33627c63f8a021a@mail.gmail.com>
References: <48BA9D65.2020001@ifi.uio.no>
<48BB4A2D.9080404@postnewspapers.com.au>
<48BBD22E.4090308@ifi.uio.no>
<dcc563d10809011051s558f8a7bp5beb0dbe181721e4@mail.gmail.com>
<a1ec7d000809011146x456b942eof33627c63f8a021a@mail.gmail.com>
"Scott Carey" <scott@richrelevance.com> writes:
> On Raid Controllers and Dev machines:
>
> For a dev machine the battery backup is NOT needed.
>
> Battery back up makes a _production_ system faster: In production, data
> integrity is everything, and write-back caching is dangerous without a
> battery back up.
>
> So:
> Without BBU: Write-through cache = data safe in power failure; Write back
> cache = not safe in power failure.
> With BBU : Both modes are safe on power loss.
This could be read the wrong way. With a BBU it's not that you can run the
drives in write-back mode safely. It's that you can cache in the BBU safely.
The drives still need to have their write caches off (ie, in write-through
mode).
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
Get trained by Bruce Momjian - ask me about EnterpriseDB's PostgreSQL training!
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To: pgsql-performance@postgresql.org
Cc: stark@enterprisedb.com, scott@richrelevance.com, scott.marlowe@gmail.com, tfinneid@student.matnat.uio.no, craig@postnewspapers.com.au
Subject: Re: slow update of index during insert/copy
In-Reply-To: <873akjodqb.fsf@oxford.xeocode.com>
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