From: | Bill Moran <wmoran(at)collaborativefusion(dot)com> |
---|---|
To: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
Cc: | Jim Nasby <decibel(at)decibel(dot)org>, Postgresql list Performance <pgsql-performance(at)postgresql(dot)org> |
Subject: | Filesystem fragmentation (Re: Fragmentation of WAL files) |
Date: | 2007-04-26 13:14:32 |
Message-ID: | 20070426091432.274977fe.wmoran@collaborativefusion.com |
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Lists: | pgsql-performance |
In response to Heikki Linnakangas <heikki(at)enterprisedb(dot)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(at)collaborativefusion(dot)com
Phone: 412-422-3463x4023
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