[SOLVED] erased Arch. reiserfsck rescue?

kanonmat · 2008-12-02 04:21:07

I managed to destroy my Arch partition. (I was just about to backup, promise.) Since grub couldn't boot my freebsd, I made a floppy to boot it with. It didn't work and I think it wrote to the MBR. I was unable to restore grub with the Arch cd. (error 17, fs type unknown, partition type 0x82)

Grub was installed from Arch. Arch was wholly installed on reiserfs, because I wanted to "have fun". The Arch wiki states that /boot/ should be on a separate ext2 partition. Why is that? ((IIRC freebsd's sysinstall says something like: bla bla, journaling or something can make tmp files too large for the partition, bla bla.)) Does /boot/ have to be a primary?

I was able to boot into debian with the "super grub disk" floppy. http://www.supergrubdisk.org
I cannot mount the fs on Arch.

me@puter# fsck -t reiserfs /dev/hda2 
fsck 1.41.3 (12-Oct-2008)
reiserfsck 3.6.19 (2003 www.namesys.com)

*************************************************************
** If you are using the latest reiserfsprogs and  it fails **
** please  email bug reports to reiserfs-list@namesys.com, **
** providing  as  much  information  as  possible --  your **
** hardware,  kernel,  patches,  settings,  all reiserfsck **
** messages  (including version),  the reiserfsck logfile, **
** check  the  syslog file  for  any  related information. **
** If you would like advice on using this program, support **
** is available  for $25 at  www.namesys.com/support.html. **
*************************************************************

Will read-only check consistency of the filesystem on /dev/hda2
Will put log info to 'stdout'

Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes
bread: Cannot read the block (2): (Invalid argument).
reiserfs_open: bread failed reading block 2
bread: Cannot read the block (16): (Invalid argument).
reiserfs_open: bread failed reading block 16

reiserfs_open: the reiserfs superblock cannot be found on /dev/hda2.
Failed to open the filesystem.

If the partition table has not been changed, and the partition is
valid  and  it really  contains  a reiserfs  partition,  then the
superblock  is corrupted and you need to run this utility with
--rebuild-sb.

Is it beyond repair? Any hints before I do "reiserfsck --rebuild-sb /dev/hda2"? I don't really know what that will do.

--rebuild-sb
This option recovers the superblock on a Reiserfs partition. Normally you only need this option if
mount reports "read_super_block: can't find a reiserfs file system" and you are sure that a Reis-
erfs file system is there. But remember that if you have used some partition editor program and now
you cannot find a filesystem, probably something has gone wrong while repartitioning and the start
of the partition has been changed. If so, instead of rebuilding the super block on a wrong place
you should find the correct start of the partition first.

How do I use the start of the partition?
I don't mind a reinstall, but I'd like to salvage some config files. xorg.conf was a pain. (undocumented monitor)

I have:
Super Grub Disk floppy
a partition table with sizes in chs format. Don't know if it was done with cfdisk or if it's up to date.
functioning debian install
copy of the old menu.lst

Last edited by kanonmat (2008-12-06 03:33:13)

kanonmat · 2008-12-04 02:42:19

cfdisk gives a table that matches the old partition table, only now the Arch partition is marked "Unusuable".
using parted with the known start and end sectors:

me@puter# parted
(parted) unit s                                                           
(parted) rescue 1012095 12723479
(parted)

Result: nothing.

Is this the right syntax?
Maybe next step is:
(parted) mkpartfs ext2 reiserfs 1012095 12723479
Is that safe?
And then:

Any fun rescue apps/recovery cd:s out there?

Last edited by kanonmat (2008-12-04 02:55:27)

MoonSwan · 2008-12-04 09:22:35

I use testdisk and gParted a lot for this sort of thing. Testdisk is on the gParted Live cd and is fairly simple to use. Thats where I would start I think.

By the way, hello from BB.

kanonmat · 2008-12-06 03:32:31

Hello, BB!
Nice to see you.

This is solved now, more or less. Arch is recovered, all files intact and some of them backed up The system seems all right, but how would I know? I learned some things (about dd and losetup) by trying the harder way, when it didn't work I just let testdisk analyse and write the partition table and automagically the partition was restored. It felt like cheating.
Minor things were that the swap got marked bootable and partitions changed device names. I had to use the boot floppy the first time, to get it up and running (and I think I'll repartition).

parted seems like a blunt tool. Debians version of testdisk said it didn't have support for reiser at compile time, so I used SystemRescueCd:
http://www.sysresccd.org/Main_Page
Maybe I could have edited it before it was burned.

What I really wanted to do was something like "@nT$" comment on:
http://antrix.net/journal/techtalk/reis … o.comments
I sacrificed the freebsd partition and made a reiserfs on it, mounted and used dd to copy the exact sectors (6 Gb in 35 min) of the area where the old partition used to be. Does block size of the fs matter? Then I mounted that image, tried to set it up as a loop device to let reiserfsck loose on it with --rebuild-sb and --rebuild-tree. It wasn't meant to happen.

Anyway:
Like in the games: Save early, save often.

Last edited by kanonmat (2008-12-06 03:35:40)

MoonSwan · 2008-12-06 09:14:27

Hi (again)! I don't know squat about block sizes, sorry. Next time you need/want to use that reiser command, try this:

mount -t reiser -o remount ro /dev/sdX /mount/path/here

where the "-o remount ro" should remount your partition in read only mode so it can be safely fsck'd or fixed by the reiser utilities.

I use the gParted or arch dvd as my rescue discs usually but sysrescue is also quite good from what i've heard.

Live and learn I suppose. Welcome to the Arch experience.

Arch Linux

#1 2008-12-02 04:21:07

[SOLVED] erased Arch. reiserfsck rescue?

#2 2008-12-04 02:42:19

Re: [SOLVED] erased Arch. reiserfsck rescue?

#3 2008-12-04 09:22:35

Re: [SOLVED] erased Arch. reiserfsck rescue?

#4 2008-12-06 03:32:31

Re: [SOLVED] erased Arch. reiserfsck rescue?

#5 2008-12-06 09:14:27

Re: [SOLVED] erased Arch. reiserfsck rescue?

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