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Re: Fragmentation of WAL files

From: Greg Smith <gsmith(at)gregsmith(dot)com>
To: Postgresql list Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Fragmentation of WAL files
Date: 2007-04-27 04:50:55
Message-ID: (view raw or whole thread)
Lists: pgsql-performance
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

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

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 (ZIP file wrapped into EXE, 

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(at)gregsmith(dot)com Baltimore, MD

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