Repairing ReiserFS file system with reiserfsck

Posted on in Categories CentOS, Data recovery, Debian Linux, File system, Linux, Troubleshooting last updated November 15, 2007
Repairing ReiserFS file system with reiserfsck

The idea and commands in this article submitted by Jacques Wagener via email. In his own words, “After nuking my partition by accident (and through my stupidity) I was really disappointed in myself, especially in losing my bookmarks and rss-feeds“. The following article is based upon our email communication. I am just putting them as an article.

We have already written about ext2/ext3 file repair using fsck and other utilities. Linux comes with different filesystems and different repair utilities. To repair a ReiserFS filesystem you need to run reiserfsck command, which is a checking tool for the ReiserFS filesystem (just like fsck command for ext2/ext3 file system).

Reiserfsck searches for a Reiserfs filesystem on a device, replays any necessary transactions, and either checks or repairs the file system. ReiserFS saves data or log in a special file for pending disk updates and later on it commit updates to disk resulting into very good filesystem consistency.

Step # 1: Install reiserfsck

You need to install reiserfsprogs package, which includes reiserfsck user level tools for ReiserFS filesystems.
# apt-get install reiserfsprogs

Or if you are using RedHat/Fedor Core Linux:
# yum install reiserfsprogs

Step # 2: Backup partition/disk

Take system down to runlevel 1.
# init 1

Unmount /dev/sda1 (if it is still mounted as read/write only):
# umount /dev/sda1; umount /dev/sda2

Before using any one of the following command you are strongly advised to make a backup copy of the whole partition using dd or ddrescue (recommended) command.
# ddrescue /dev/sda /dev/sdb

OR use dd command:
# dd if=/dev/sda of=/dev/sdb conv=noerror

Step # 3: Check filesystem consistency

Above command makes a backup of your drive. Next check filesystem consistency which will reports problem to you with the following command (assuming that /dev/sda1 is your partition):
# reiserfsck --check /dev/sda1

If you get an error Bad root block 0If you get following message:
Running with –rebuild-tree is required

Then you need to run following command rebuilds the entire filesystem tree using leaf nodes found on the device (this is nothing but indication of corrupted :
# reiserfsck --scan-whole-partition --rebuild-tree /dev/sda1


  • –scan-whole-partition: This option causes –rebuild-tree to scan the whole partition but not only the used space on the partition. You should always use this option with –rebuild-tree.
  • –check: Checks filesystem consistency and reports, but does not repair any corruption that it finds.
  • –rebuild-tree: This option rebuilds the entire filesystem tree using leaf nodes found on the device. Once you passed this option, do not stop or interrupt building operating.

Recovering corrupted superblock

Each file system has a superblock, which contains information about file system such as:

  • File system type
  • Size
  • Status
  • Information about other metadata structures

If this information lost, you are in trouble (data loss) so Linux maintains multiple redundant copies of the superblock in every file system.

During check (reiserfsck –check /dev/sda1) if you get an error superblock was missing, use following command to fix superblock:
# reiserfsck --rebuild-sb /dev/sda1


  • –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”.

Caution: Do not run above command twice on same drive. You will damage your partition (data).

Final note

Next logical step is mount your partition /dev/sda1 and check for your data:
# mkdir -p /mnt/data
# mount /dev/sda1 /mnt/data
# cd /mnt/data
# ls
# ls lost+found/ -l

lost+found is a special directory where recovered files are kept by Linux/reiserfsck. You can examine these files and restore the data.

Better backup entire partition using tar or ssh session:
# tar cvf /dev/nst0 /mnt/data

OR use scp to dump data to remote system:
# scp -r /mnt/data [email protected]:/backup

See also:

13 comment

  1. Tried it. It didn’t work. I ended up using a WINDOWS program called “UFS Explorer” – yes, I paid the $22.95 for it – and it recovered most of my needed data. Running on Windows. I’m sorry, but that’s just wrong, when Linux should be better at dealing with Linux filesystems.

    One utility that is needed, if we’re going to put Linux on many desktops, is a utility to read an unmounted drive and recover the data from it without depending on the superblock, inodes, et cetera. I don’t know what, exactly, UFS Explorer does to do its thing, but it does it very nicely. Other utilities are out there that do this; at least one runs in java (okay, crawls in java): rossifstools. It doesn’t do it as well as UFS explorer does, though. And rfstools just sucks; it balks when the filesystem is not whole and intact.

  2. Ian, sorry to hear that it didn’t worked out for you but it did worked for Jacques. Data recovery is complicated topic (procedure) and it needs some expertise/experience.

  3. I need to fix my swap partition, apparently. I can see all my files are there, using the CAT command, but I can’t get an xterm. The filesystem is read-only. I was confused by the first error message that told me to run fsck when I need to run reiserfsck, apparently, having consulted my SUSE 10 manual. I have never managed to run reiserfsck, because I chickened out after it asked me for the block size (did it also give 4096 by default, then?) and I think the initial number. Now this information is telling me I need to back up evreything and remount it and all this stuff, when the error message seems to suggest it’s not a big deal; it wants me to run reiserfs and fix some bad pointer.

    Can someone tell me both the correct syntax for doing this as well as how I find out the correct parameters before I try it?

    I got so far as checking the partition, which tells me that I have a corrupted superblock. Then when I try to rebuild the superblock, it starts asking me all these questions I’m not sure about, and I don’t want to lose two months of work here.

    I’ll be happy to consult the right man pages if I could figure out which one is really appropriate.

  4. This is an update of my preceding. It’s not my swap partition; it’s the root partition. I thought it was the swap partitition from misreading the “failed to load hda5” as it flashed by the bootup diagnostics.

    Now I have run residerfsck — check and learned that I have a Problem in Internal Tree 2/120 (of 168)/19 (of 170) there at block 65885, and I need to rebuild the tree, not the superblock. The man pages say it “strongly recommends” that I back up the data before I proceed, but how am I supposed to do that when the partition is now mounted “read only.” All the critical data would fit on a small flash drive, but like any other media, it has a mount point which is now “read only.”

    Isn’t this a contradiction, to recommend a backup for a partition that has been mounted read only?

  5. Hi,
    I write
    “reiserfsck –check /dev/sdb5”

    and the system show me this message
    “Will read-only check consistency of the filesystem on /dev/sdb5
    Will put log info to ‘stdout’

    Do you want to run this program?[N/Yes] (note need to type Yes if you do):”

    Then i type:

    An system show this
    reiserfsck –check started at Sat Dec 26 10:13:53 2009
    Replaying journal..
    Reiserfs journal ‘/dev/sdb5’ in blocks [18..8211]: 0 transactions replayed
    Checking internal tree..

    Bad root block 0. (–rebuild-tree did not complete)

    [email protected]:~$ sudo reiserfsck –scan-whole-partition –rebuild-tree /dev/sdb5
    reiserfsck 3.6.19 (2003”

    I wait 2 days for any answer on diferents forum, then i try this comands
    reiserfsck –scan-whole-partition –rebuild-tree /dev/sdb5

    Then system show this message
    “reiserfsck 3.6.19 (2003

    ** Do not run the program with –rebuild-tree unless **
    ** something is broken and MAKE A BACKUP before using it. **
    ** If you have bad sectors on a drive it is usually a bad **
    ** idea to continue using it. Then you probably should get **
    ** a working hard drive, copy the file system from the bad **
    ** drive to the good one — dd_rescue is a good tool for **
    ** that — and only then run this program. **
    ** If you are using the latest reiserfsprogs and it fails **
    ** please email bug reports to [email protected], **
    ** 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 **

    Will rebuild the filesystem (/dev/sdb5) tree
    Will put log info to ‘stdout’

    Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes
    Replaying journal..
    Reiserfs journal ‘/dev/sdb5’ in blocks [18..8211]: 0 transactions replayed
    reiserfsck –rebuild-tree started at Sat Dec 26 10:22:01 2009

    Pass 0:
    ####### Pass 0 #######
    The whole partition (122093984 blocks) is to be scanned”

    I have 1 day and 3 hors waitin.
    I calculate that this work take 10 days,¿¿is this normal??


    Sorry for my english….

  6. What if your device is a raid 1 device where both of the individual raid members check out fine but the started array won’t mount. Bad root block 0. (–rebuild-tree did not complete)

    dmesg | tail outputs:

    reiserfs: using flush barriers
    [ 8949.733728] REISERFS (device md127): journal params: device md127, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
    [ 8949.734383] REISERFS (device md127): checking transaction log (md127)
    [ 8950.019610] REISERFS warning: reiserfs-5090 is_tree_node: node level 29951 does not match to the expected one -1
    [ 8950.019618] REISERFS error (device md127): vs-5150 search_by_key: invalid format found in block 0. Fsck?
    [ 8950.019623] REISERFS (device md127): Remounting filesystem read-only
    [ 8950.019630] REISERFS error (device md127): vs-13070 reiserfs_read_locked_inode: i/o failure occurred trying to find stat data of [1 2 0x0 SD]
    [ 8950.019641] REISERFS warning: reiserfs-5090 is_tree_node: node level 29951 does not match to the expected one -1
    [ 8950.019645] REISERFS error (device md127): vs-5150 search_by_key: invalid format found in block 0. Fsck?

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