Re: Raw devices vs. Filesystems

From: Chris Browne <cbbrowne(at)acm(dot)org>
To: pgsql-admin(at)postgresql(dot)org
Subject: Re: Raw devices vs. Filesystems
Date: 2004-04-06 20:57:02
Message-ID: 603c7gj04h.fsf@dev6.int.libertyrms.info
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gsw(at)globexplorer(dot)com ("Gregory S. Williamson") writes:
> No point to beating a dead horse (other than the sheer joy of the
> thing) since postgres does not have raw device support, but ... raw
> devices, at least on solaris, are about 10 times as fast as cooked
> file systems for Informix. This might still be a gain for postgres'
> performance, but the portability issues remain.

That claim seems really rather remarkable.

It implies an entirely stunning degree of inefficiency in the
implementation of filesystems on Solaris.

The amount of indirection involved in walking through i-nodes and such
is something I would expect to introduce some percentage of
performance loss, but for it to introduce overhead of over 900%
presumably implies that Sun (and/or Veritas) got something really
horribly wrong.
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