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Date: Wed, 19 Oct 2011 17:15:48 -0500 (CDT)
From: Robert Bonomi <bonomi@mail.r-bonomi.com>
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To: freebsd-questions@freebsd.org
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Subject: Re: small du(1) question
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> Date: Wed, 19 Oct 2011 20:47:54 +0000
> From: Alexander Best <arundel@freebsd.org>
> Subject: Re: small du(1) question
>
> the blocksize of the underlying filesystem, shouldn't the output of
> 'du -A -B4096' and 'du -A' be the same? just tested this on freebsd 7 and
> freebsd 10 and the outputs differ.
>

"So much for the theory", one might say. <wry grin>

The answer to your 'intended as rhetorical' question is 'no'.

Filesystems have 'overhead' on a per-file basis, as well as 'filesystem'
(as a whole) basis.  Do you know about 'index blocks' for files that are
more than one block long?   Does the size of the index block change if
the blocksize of ghe underlying filesystem is different?  Does the -A
option include the index block(s), if any?  Do I need to keep asking
questions ?    *grin*