Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 13 Dec 2001 10:48:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 13 Dec 2001 10:48:49 -0500 Received: from neuron.com ([209.61.186.37]:25865 "EHLO server1.neuron.com") by vger.kernel.org with ESMTP id ; Thu, 13 Dec 2001 10:48:35 -0500 Date: Thu, 13 Dec 2001 09:56:53 -0600 (CST) From: To: Jesse Pollard cc: , Subject: Re: passing params to boot readonly In-Reply-To: <200112131501.JAA41764@tomcat.admin.navo.hpc.mil> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 13 Dec 2001, Jesse Pollard wrote: > --------- Received message begins Here --------- > > > > > On December 12, 2001 21:50, Stewart Allen wrote: > > > I'm in a bit of a pickle and need to find a way to pass boot params to a > > > reiserfs rootfs to *prevent* it from replaying the journal on single-user > > > boot. This may seem like a strange request, but I've got a degraded RAID > > > array that I need to poke around in before deciding whether or not to send > > > a disk off to a rehab lab. If the replay occurs, it will potentially > > > destroy the fs since I'm using a degraded snapshot of the failed disk in > > > hopes of reclaiming *some* of my data. The system is running 2.2.x (can't > > > remember and can't find out w/out booting). > > > > > > Do I have a snowball's chance of pulling this off? > > > > Well, kinda. The only thing that can deter ReiserFS from replaying the > > journal is convincing it that the physical media it's on is actually read > > only. Some quick less/grep work revealed that there is no option that makes > > the SCSI subsystem claim its devices are readonly (although it'd be extremely > > useful for situations such as this). > > > > It'd probably be pretty easy to make a boot disk using a hacked version of > > ReiserFS that refuses to replay the journal, by adding a "return 0;" near the > > top of journal_read(struct super_block *) in journal.c. However, you might > > feel more comfortable sending it off for data recovery than testing kernel > > hacks on it ;) > > Wouldn't it be better to make a backup (dd copy) of the disk volume to another > drive? The raid would not be mounted, so the fs would not be updated. > > I would recommend that be done even before sending the disk out. > > ALTERNATIVE TO READ-ONLY and this might not be possible. > > If the raid is SCSI based, then there is (should be) a read-only switch > in the disk configuration. Most disks do not have a jumper there, and since > they are usually internal only, the option is not used. Putting the jumper > on (or removing one if it is there - depends on the drive) will make the > disk read-only. > > Even some IDE drives may have this option, though finding documentation on > it may be difficult to locate. > ------------------------------------------------------------------------- > Jesse I Pollard, II > Email: pollard@navo.hpc.mil > > Any opinions expressed are solely my own. The RAID array uses 3ware's Escalade switch so all the drives are EIDE. I've used read-only jumpers on SCSI drives in the past and hoped that these supported it as well, but when I took the array apart, my hopes were dashed. The drive that crashed will not spin up so I cannot dd back it up. I will be doing this with two of the other disks, which should comprise a complete (if degraded) image set. stewart - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/