From owner-freebsd-fs Fri Jan 31 11: 1:18 2003 Delivered-To: freebsd-fs@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D11C737B401; Fri, 31 Jan 2003 11:01:16 -0800 (PST) Received: from mcomail01.maxtor.com (mcomail01.maxtor.com [134.6.76.15]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3590F43F75; Fri, 31 Jan 2003 11:01:16 -0800 (PST) (envelope-from stephen_byan@maxtor.com) Received: from mcoexc03.mlm.maxtor.com (localhost.localdomain [127.0.0.1]) by mcomail01.maxtor.com (8.11.6/8.11.6) with ESMTP id h0VIofM04700; Fri, 31 Jan 2003 11:50:41 -0700 Received: from mmans02.mma.maxtor.com ([134.6.232.101]) by mcoexc03.mlm.maxtor.com with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) id D4XRKYLV; Fri, 31 Jan 2003 12:01:08 -0700 Received: from maxtor.com by mmans02.mma.maxtor.com (8.8.8/1.1.22.3/08May01-0432PM) id OAA0000002209; Fri, 31 Jan 2003 14:00:57 -0500 (EST) Date: Fri, 31 Jan 2003 14:00:55 -0500 Subject: Re: DEV_B_SIZE Content-Type: text/plain; charset=US-ASCII; format=flowed Mime-Version: 1.0 (Apple Message framework v551) Cc: phk@freebsd.org, freebsd-fs@freebsd.org, tech-kern@netbsd.org To: David Laight From: Steve Byan In-Reply-To: <20030131185507.G1487@snowdrop.l8s.co.uk> Message-Id: <538478DE-354E-11D7-B26B-00306548867E@maxtor.com> Content-Transfer-Encoding: 7bit X-Mailer: Apple Mail (2.551) Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org On Friday, January 31, 2003, at 01:55 PM, David Laight wrote: >> Really? fsck can recover from losing 4K bytes surrounding the last >> metadata block written? > > The only metadata that matter are the inodes and (for ffs) the > indirect blocks. You do really want the latter to be single disk > blocks - many systems actually write them synchonously. What could be the effect of losing surrounding blocks on the (failed) write of an indirect block? Can we guarantee that fsck can reconstruct the filesystem, modulo some recently-created or deleted files, or is there a possibility of losing the entire filesystem? > The inode is (probably) only 128 bytes, losing an inode block > will lose the other files. > > A journaling filesystem probably already has ways around this... I think journaling filesystems need to know the atomic block size in order to structure their log in a fault-tolerant way; I'm hoping someone on these lists can provide some details. Regards, -Steve -------- Steve Byan Design Engineer Maxtor Corp. MS 1-3/E23 333 South Street Shrewsbury, MA 01545 (508) 770-3414 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message