From: Greg Smith <gsmith@gregsmith.com>
To: Postgresql list Performance <pgsql-performance@postgresql.org>
Subject: Re: Fragmentation of WAL files
Date: Fri, 27 Apr 2007 00:50:55 -0400 (EDT)
Message-ID: <Pine.GSO.4.64.0704270019060.8684@westnet.com> (raw)
In-Reply-To: <20070426080050.522ef7b5.wmoran@collaborativefusion.com>
References: <3BD44C5D-E402-43EB-8FFD-1A4BC97AFD0C@decibel.org>
<20070426080050.522ef7b5.wmoran@collaborativefusion.com>
On Thu, 26 Apr 2007, Bill Moran wrote:
> I've seen marketing material that claims that modern NTFS doesn't suffer
> performance problems from fragmentation.
You're only reading half of the marketing material then. For a balanced
picture, read the stuff generated by the companies that sell defragmenting
tools. A good one to start with is
http://files.diskeeper.com/pdf/HowFileFragmentationOccursonWindowsXP.pdf
Going back to the Jim's original question, they suggest a Microsoft paper
that talks about how the defrag report can be misleading in respect to
open files. See http://support.microsoft.com/kb/228198
Also, some of the most interesting details they gloss over are specific to
which version of Windows you're using; the reference guide to the subject
of how NTFS decides how much space to pre-allocate at a time is available
at http://support.microsoft.com/kb/841551 (ZIP file wrapped into EXE,
yuck!)
If you compare them, you can see that the approach they're using in NTFS
has evolved to become more like that used by a good UNIX filesystem over
time. I think your typical UNIX still has a healthy lead in this area,
but the difference isn't as big as it used to be.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
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To: pgsql-performance@postgresql.org
Cc: gsmith@gregsmith.com
Subject: Re: Fragmentation of WAL files
In-Reply-To: <Pine.GSO.4.64.0704270019060.8684@westnet.com>
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