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Home - Linux - Ext3 - Bad Disk

Anyway, when my machine recently crashed, it produced a "Short Read" error when running fsck on the device. This is bad news, and to me indicates that the disk is going bad. If could be just a bad block, but I'm preparing for the worst. This error occured consistently, and eventually caused programs like "touch" and "mkdir" to hang on my machine, and of course, the machine won't reboot properly. My solution:

• First, turn off all programs that use the filesystem that is damaged. This might not always be possible, but is possible in my case. Check /etc/rc.d/init.d/* and /etc/rc.d/rc.local, cron jobs, at jobs, and possibly even remote access.
• remove the filesystem from /etc/fstab (comment it out)
• reboot (in my case, I needed hard reboot).
• when the machine comes back up, then as root run fsck on the corrupt (unmounted) file system, in my case it's /dev/hdb7

  [root@jack /]# fsck /dev/hdb7
  

  Fix whatever errors you can, you will probably still see the "short read" error.
• There is a command called "e2fsck -c" (assuming it's a ext2 or ext3 file system). This will add any bad blocks it finds to the bad block list! This will take a while, (took ages on my 20g partition) and is pretty much guaranteed that you will lose files that were on your filesystem. In my case, I don't much care about the files :-)

  [root@jack /]# e2fsck -c /dev/hdb7
  e2fsck 1.23, 15-Aug-2001 for EXT2 FS 0.5b, 95/08/09
  Checking for bad blocks (read-only test):   3913488/  4963636
  Pass 1: Checking inodes, blocks, and sizes
  Pass 2: Checking directory structure
  Entry 'flamingtext_com.160921022.jpg' in /doc/hmail/01/10/20 (2404713) points to inode (2405633) located in a bad block.
  Clear? 
  ...
  Free inodes count wrong (2079467, counted=2079292).
  Fix? 
  ...
  /dev/hdb7: ***** FILE SYSTEM WAS MODIFIED *****
  /dev/hdb7: 406212/2485504 files (4.2% non-contiguous), 1626275/4963636 blocks
  

  So as you can see above, this is will delete some files.
• Since the file system should be clean, you can force a check using:

  [root@jack /]# fsck -f /dev/hdb7
  e2fsck 1.23, 15-Aug-2001 for EXT2 FS 0.5b, 95/08/09
  Pass 1: Checking inodes, blocks, and sizes
  Pass 2: Checking directory structure
  Pass 3: Checking directory connectivity
  Pass 4: Checking reference counts
  Pass 5: Checking group summary information
  /dev/hdb7: 406212/2485504 files (4.2% non-contiguous), 1626275/4963636 blocks
  [root@jack /]# 
  
  

• Now I mount the file system not in it's regular place. This is to make sure that other programs don't start using it, and make it hard to unmout:

  [root@jack /]# mkdir /junk
  [root@jack /]# mount /dev/hdb7 /junk
  [root@jack /]# cd /junk
  [root@jack junk]# ls
  total 24
     4 doc/    16 lost+found/     4 var/
  [root@jack junk]# 
  

  I then proceeded to run a few little tests, touch, mkdir, find . -print > /dev/null etc. then forced another check.

  [root@jack /]# fsck -f /dev/hdb7
  Parallelizing fsck version 1.23 (15-Aug-2001)
  e2fsck 1.23, 15-Aug-2001 for EXT2 FS 0.5b, 95/08/09
  Pass 1: Checking inodes, blocks, and sizes
  Pass 2: Checking directory structure
  Pass 3: Checking directory connectivity
  Pass 4: Checking reference counts
  Pass 5: Checking group summary information
  /dev/hdb7: 406205/2485504 files (4.2% non-contiguous), 1626254/4963636 blocks
  [root@jack /]# 
  

  Now the question is, am I feeling lucky? I could do another e2fsck -c /dev/hdb7, and I'll probably regret not doing that, but I'm feeling lucky (against my better judgement). But I don't add it back into /etc/fstab, I just mount manually, so if it reboots, it won't cause any trouble. No doubt, I'll forget, and then when it does reboot, I'll wonder why that file system is gone.

Last Change: Monday, 10-Jan-2005 07:40:51 EST

Disclaimer

The information provided within these pages is provided AS IS, and without any warranty. Following these directions may (but not limited to) crash your computer, delete all the information on your hard disk, open up security holes or cause your house to burn down. I made these pages to provide some information about the setup that I have done, but I did not proofread it for correctness, and in most cases did not test it. There are commands in these pages that would definately delete or corrupt all the data on your computer (especially the dualboot section). In fact it happened to me.... So you are on your own!