From owner-freebsd-hackers Thu May 6 15:45:22 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from sol (cs1-gw.cs.binghamton.edu [128.226.171.72]) by hub.freebsd.org (Postfix) with SMTP id 14ACC14CCB for ; Thu, 6 May 1999 15:45:15 -0700 (PDT) (envelope-from zzhang@cs.binghamton.edu) Received: from localhost (zzhang@localhost) by sol (SMI-8.6/8.6.9) with SMTP id SAA16568; Thu, 6 May 1999 18:34:33 -0400 Date: Thu, 6 May 1999 18:34:33 -0400 (EDT) From: Zhihui Zhang To: Mike Smith Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Boot blocks Questions (was: superblocks in FFS) In-Reply-To: <199905062232.PAA01917@dingo.cdrom.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > > > Thanks for the fastest reply I have ever got! For this above point, the > > beginning of a FreeBSD slice should belong to the cylinder group 0 of the > > first filesystem in the slice, although this filesystem may not be the > > root filesystem. Am I right? > > Not entirely. > > In order to simplify offset calculations, there's a large gap at the > beginning of the filesystem. If the filesystem starts at the very > bottom of the slice, this gap will contain the disklabel and > bootblocks. If the filesystem is elsewhere, it's just empty. > Let me put my understanding in your words: (1) The gap is BBSIZE bytes or 16 sectors. (2) This gap does not belong to cylinder group 0 and the size of cylinder group 0 is BBSIZE less than other cylinder groups. But if you say this gap belongs to cylinder group 0 (the block bitmap will not include them of course), then all cylinder groups are of the same size (the last cylinder group may of a different size). -Zhihui To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message