From: Craig A. James <cjames@modgraph-usa.com>
To: Bill Moran <wmoran@collaborativefusion.com>
Cc: Heikki Linnakangas <heikki@enterprisedb.com>
Cc: Postgresql list Performance <pgsql-performance@postgresql.org>
Subject: Re: Filesystem fragmentation (Re: Fragmentation of WAL files)
Date: Thu, 26 Apr 2007 09:35:02 -0700
Message-ID: <4630D4B6.9040802@modgraph-usa.com> (raw)
In-Reply-To: <20070426091432.274977fe.wmoran@collaborativefusion.com>
References: <3BD44C5D-E402-43EB-8FFD-1A4BC97AFD0C@decibel.org>
<20070426080050.522ef7b5.wmoran@collaborativefusion.com>
<463096AD.4020707@enterprisedb.com>
<20070426091432.274977fe.wmoran@collaborativefusion.com>
Bill Moran wrote:
> In response to Heikki Linnakangas <heikki@enterprisedb.com>:
>>>> 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.
More specifically, this problem was solved on UNIX file systems way back in the 1970's and 1980's. No UNIX file system (including Linux) since then has had significant fragmentation problems, unless the file system gets close to 100% full. If you run below 90% full, fragmentation shouldn't ever be a significant performance problem.
The word "fragmentation" would have dropped from the common parlance if it weren't for MS Windoz.
Craig
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To: pgsql-performance@postgresql.org
Cc: cjames@modgraph-usa.com, wmoran@collaborativefusion.com, heikki@enterprisedb.com
Subject: Re: Filesystem fragmentation (Re: Fragmentation of WAL files)
In-Reply-To: <4630D4B6.9040802@modgraph-usa.com>
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