From: Bill Moran <wmoran@collaborativefusion.com>
To: Heikki Linnakangas <heikki@enterprisedb.com>
Cc: Jim Nasby <decibel@decibel.org>
Cc: Postgresql list Performance <pgsql-performance@postgresql.org>
Subject: Filesystem fragmentation (Re: Fragmentation of WAL files)
Date: Thu, 26 Apr 2007 09:14:32 -0400
Message-ID: <20070426091432.274977fe.wmoran@collaborativefusion.com> (raw)
In-Reply-To: <463096AD.4020707@enterprisedb.com>
References: <3BD44C5D-E402-43EB-8FFD-1A4BC97AFD0C@decibel.org>
<20070426080050.522ef7b5.wmoran@collaborativefusion.com>
<463096AD.4020707@enterprisedb.com>
In response to Heikki Linnakangas <heikki@enterprisedb.com>:
[snip]
> >> Can anyone else confirm this? I don't know if this is a windows-only
> >> issue, but I don't know of a way to check fragmentation in unix.
> >
> > I can confirm that it's only a Windows problem. No UNIX filesystem
> > that I'm aware of suffers from fragmentation.
>
> What do you mean by suffering? All filesystems fragment files at some
> point. When and how differs from filesystem to filesystem. And some
> filesystems might be smarter than others in placing the fragments.
To clarify my viewpoint:
To my knowledge, there is no Unix filesystem that _suffers_ from
fragmentation. Specifically, all filessytems have some degree of
fragmentation that occurs, but every Unix filesystem that I am aware of
has built-in mechanisms to mitigate this and prevent it from becoming
a performance issue.
> There's a tool for Linux in the e2fsprogs package called filefrag that
> shows the fragmentation of a file, but I've never used it myself.
Interesting. However, the existence of a tool does not particularly
indicated the _need_ for said tool. It might just have been something
cool that somebody wrote.
--
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/
wmoran@collaborativefusion.com
Phone: 412-422-3463x4023
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To: pgsql-performance@postgresql.org
Cc: wmoran@collaborativefusion.com, heikki@enterprisedb.com, decibel@decibel.org
Subject: Re: Filesystem fragmentation (Re: Fragmentation of WAL files)
In-Reply-To: <20070426091432.274977fe.wmoran@collaborativefusion.com>
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