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Re: Harddisk gone bad (longish)

OK, got the new drive (will be getting a RAID card and another drive too to
do RAID1 for data security!) and did the image xfer (dd etc)

Then ran e2salvage on it (kewl program!!!)
Then ran e2fsck again to restore the superblocks... The superblock that
saved me was the 10TH!!!!

It is now copying old data to the new disc, after that we'll have to
investigate whether and how much data is still valid...

Thx for the advice ya'll tho! I wouldn't have made it without the hints,
tips and pointers!


----- Original Message -----
From: "Francesco Peeters" <Francesco linuxprive yi org>
To: "Theodore Ts'o" <tytso mit edu>
Cc: <ext3-users redhat com>
Sent: Tuesday, November 12, 2002 12:04 AM
Subject: Re: Harddisk gone bad (longish)

> > On Sun, Nov 10, 2002 at 08:55:26PM +0100, Francesco Peeters wrote:
> <SNIP>
> >
> > I suppose one of these days someone really should write a "hard disk
> > catastrophe" HOWTO.....
> That'd be cool!
> >
> > When you have a lot of precious data on a disk that hasn't been backed
> > up.  The very **first** thing you should do is to get the cursing
> > yourself for being twenty different kinds of full for not having a
> > backup system out of your system.  Get that out of your system, so you
> > don't make any further mistakes.....
> LOL... Done that!!!
> >
> > Next, get yourself a backup hard drive which is at least as big as the
> > disk which is in trouble, and do a full disk-to-disk copy of the disk
> > that's in trouble:
> >
> > dd if=/dev/hdc of=/dev/hdd bs=1k conv=sync,noerr
> >
> > Do this right away, because if the problem was due to hardware
> > failure, you want to grab a snapshot before the disk gets any worse.
> That's happening right now...
> >
> > For experimental purposes, if you're not sure what you're doing, it's
> > useful to get another spare disk, and make a second-generation copy
> > from your first primary backup.  That way, you can experiment on the
> > second-generation copy, and if one recovery technique doesn't work,
> > you can try again with a different technique, and not have to worry
> > about making any irrecoverable mistakes.
> Was planning on doing that as well.... Waiting for a 2nd drive &
> controllercard to arrive this week... I'll then implement (hardware) RAID1
> when all data has been retrieved... (or found irreparably lost!)
> >
> > The first thing I would try at this point, is an "e2fsck -y" on the
> > second generation backup.  See what you can save when it's all done;
> > don't forget to check the lost+found directory in the root of the
> > filesystem.  Sometimes files will end up there.
> >
> > If that doesn't work, the next steps will require a lot more expertise
> > and special work.  So I'd start with that, and see how much you can
> > recover from that.
> >
> > > Now when I try to do e2fsck /dev/hdc1 I get 'a corruption was found
> > > in the superblock' When I try e2fsck -b 8193 /dev/hdc1 It claims it
> > > is not a valid superblock... The same for for instance 32679, a.s.o.
> >
> > For a 4k filesystem, the backup block is 32768.  But please, make the
> > full disk-to-disk backups first, and experiment on the backups.  That
> > way, you don't need to worry about panic-induced mistakes from making
> > the problem any worse.
> Oops! That was a typo... I meant 32768... Anyway, it didn't work... That
> the real problem!  :-( But I didn't want to go on without a backup
> >
> > - Ted
> >
> > P.S.  For those people for whom backups are just too much effort,
> > *please* consider using the "e2image" program to snapshot and backup
> > critical filesystem metadata.  It's not a replacement for doing full
> > data backups, but at least if you have an e2image dump, in the worst
> > case you'll be able to recover more files if a disk failure damages
> > your inode table.  The problem without the inode table there is no
> > record of which blocks go with which files, which means that
> > recovering files because a very, very painful manual process.  e2image
> > will create a backup copy of the inode table, which even if it is not
> > fully up-to-date, will be a help in trying to reconstruct data from a
> > filesystem after a disk failure.  Of course, the real answer is to do
> > real backups.....
> >
> >
> Until I can afford a backup system that can effectively backup all live
> (prolly gonna be an onstream drive for price/performance reasons) would it
> be possible to run e2image from cron on a daily basis?
> TIA !
> --FP
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