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From: guy@gorodish.UUCP
Newsgroups: comp.unix.wizards
Subject: Re: 4.3BSD conversion question ...
Message-ID: <16598@sun.uucp>
Date: Mon, 13-Apr-87 11:55:12 EST
Article-I.D.: sun.16598
Posted: Mon Apr 13 11:55:12 1987
Date-Received: Wed, 15-Apr-87 00:15:59 EST
References: <6810@brl-adm.ARPA> <8371@tekecs.TEK.COM> <2307@cit-vax.Caltech.Edu>
Sender: news@sun.uucp
Reply-To: guy@sun.UUCP (Guy Harris)
Organization: Sun Microsystems, Mountain View
Lines: 10

>> My question is WHY does fsck (or anything else) care whether the
>> directory is a multiple of 512?
>
>Some disk controllers (Xylogics) can only do I/O in units of whole sectors.

That may be true, but it's also irrelevant.  The UNIX file system
code, as far as I can tell, always reads whole frags, and frags are
rarely if ever smaller than a sector.  (There exist 24-byte
directories on a machine here with Xylogics disk controllers and it
doesn't seem to mind.)