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Date: Fri, 22 Aug 2008 11:04:08 -0700
From: "Jared Hulbert" <jaredeh@gmail.com>
To: "=?UTF-8?Q?J=C3=B6rn_Engel?=" <joern@logfs.org>
Subject: Re: [PATCH 04/10] AXFS: axfs_inode.c
Cc: "Phillip Lougher" <phillip@lougher.demon.co.uk>,
       "Arnd Bergmann" <arnd@arndb.de>, Linux-kernel@vger.kernel.org,
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> Elsewhere in this maze of threads Arnd claimed to have tested the
> benefits of metadata compression - and it making little impact.
>
> My guess is that it would make a large impact if metadata would be a
> significant part of the filesystem image.  Usually metadata is close
> enough to 0% to be mistaken for statistical noise.  So compressing it
> makes a significant impact on an insignificant amount of data.

Like I said early it depends on the value you assign to significant.
For a fs sizes I started designing to 16MB-64MB if you have to track a
whole bunch of 8Byte numbers for every symlink, dev node, inode, and
page.  It adds up quickly to a couple of MB, that can translate to
lots of money.  Even at only an extra $0.25 a system * 12Million units
= $3Million.