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From: Robert Nordier <rnordier@iafrica.com>
Message-Id: <199706211851.UAA01816@eac.iafrica.com>
Subject: Re: root directory is not a multiple of the clustersize in length
In-Reply-To: <199706211439.WAA06656@vas.tomsk.su> from "Victor A. Sudakov" at "Jun 21, 97 10:39:34 pm"
To: vas@vas.tomsk.su (Victor A. Sudakov)
Date: Sat, 21 Jun 1997 20:51:23 +0200 (SAT)
Cc: questions@FreeBSD.ORG
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Victor A. Sudakov wrote:

> I got the sinister message:
> 
> mountmsdosfs(): Warning: root directory is not a multiple of the clustersize
> in length
> 
> when I tried to
> 
> mount -t msdos /dev/fd0.720 /mnt/diska
> 
> Weird, isn't it? Should I be afraid of it? 

There isn't actually any requirement that a DOS FS root directory
should be a multiple of cluster size.

The warning is a relic from pre-FreeBSD 2.2 days, and was *once*
useful because (in testing for something that didn't matter) it
coincidentally broke at just the right point.

A standard DOS hard disk root directory has 512 x 32 byte entries,
and is therefore 16K in size.  FreeBSD releases prior to 2.2 had
a problem dealing with FSes with a block size exceeding 16K.
(However, this problem had nothing to do with the msdosfs, directly,
or the condition being tested for.)

Since 16K is not, according to the logic used, a multiple of any
power of 2 exceeding 16K, the warning would appear whenever a DOS
FS with an effective block size exceeding 16K was mounted.  Taken
as advance notice that the VFS layer was about to chew any mounted
FS into tiny pieces, courtesy of the mounted DOS partition, the
warning was therefore useful.  And, at the same time, nonsensical.

The warning can be ignored unless you are running 2.1 (or a prior
release) on a DOS FS with a cluster size exceeding 16K.

In your case, your floppy may either be in a (prefectly acceptable)
"non-standard" format, or the floppy boot sector may be corrupt.
If the contents lists correctly, it is almost certainly just a
non-standard format.

--
Robert Nordier