Loading ...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
Where,
- --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
Where,
- --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 you@other.server.com:/backup
See also:
- Surviving a Linux Filesystem (ext2/ext3) Failures
- ReiserFS project site
- For more information consult man pages of dd, dd_rescue/ddrescue, reiserfsck, fsck
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You may also be interested in other helpful articles:
- Knoppix Linux rescue: Four Tough Lessons of System Recovery
- Hans Reiser: Once a Linux Visionary, Now Accused of Murder
- Hans Reiser Guilty of First Degree Murder
- Repairing Linux ext2 or ext3 file system
- Solaris Run level change
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Tags: check ReiserFS filesystem, dd command, ddrescue_command, dd_command, filesystem, fsck command, mount_command, partition disk, reiserfsck_command, repair utilities
This is same as old article, surviving filesystem failures. Good one
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.
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.
[...] Well, recently, I finally stumbled across something mentioning how to go about recovering stuff from a partition that has become corrupted. I thought,”Ah ha! I bet I can use this to save those photos and stuff I lost a couple of years ago!” So I went searching for more info. If you read that other article, you might think,”What else ya need to know? That seems to cover it pretty good!” Well, I have always been the type who would rather be overly informed. With the photos and stuff on that drive, I have always kinda thought, when I try to recover that stuff, I need to get it right the first time, cause that drive will die about the time I plug it back into my computer. [...]
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.
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?
Bruce,
See step # 2: Backup partition/disk
run dd command to backup data and create new image on other hard disk. You only need read only access.
Thanks for this article. This helped me repair my corrupt ReiserFS partition.