Thursday, November 27, 2014

Fix Corrupted fstab file

[root]# fdisk /dev/hdb
Command (m for help): m     (Enter the letter "m" to get list of commands)
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   l   list known partition types
   m   print this menu
   n   add a new partition
   o   create a new empty DOS partition table
   p   print the partition table
   q   quit without saving changes
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit
   x   extra functionality (experts only)

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
e
Partition number (1-4): 1
First cylinder (1-2654, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-2654, default 2654):
Using default value 2654

Command (m for help): p

Disk /dev/hdb: 240 heads, 63 sectors, 2654 cylinders
Units = cylinders of 15120 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hdb1             1      2654  20064208+   5  Extended

Command (m for help): w    (Write and save partition table)

[root]# mkfs -t ext3 /dev/hdb1
mke2fs 1.27 (8-Mar-2002)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
2508352 inodes, 5016052 blocks
250802 blocks (5.00%) reserved for the super user
First data block=0
154 block groups
32768 blocks per group, 32768 fragments per group
16288 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000

Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 34 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[root]# mkdir /opt2
[root]# mount -t ext3 /dev/hdb1 /opt2
File: /etc/fstab Red Hat 8.0
LABEL=/                 /                       ext3    defaults        1 1
LABEL=/boot             /boot                   ext3    defaults        1 2
none                    /dev/pts                devpts  gid=5,mode=620  0 0
none                    /proc                   proc    defaults        0 0
none                    /dev/shm                tmpfs   defaults        0 0
/dev/hda2               swap                    swap    defaults        0 0
/dev/hdb1               /opt2                   ext3    defaults        1 2
/dev/cdrom              /mnt/cdrom              iso9660 noauto,owner,kudzu,ro 0 0
/dev/fd0                /mnt/floppy             auto    noauto,owner,kudzu 0 0
                
The digits "1 2" refer to whether the mount point should be backed up when the dump command is used and disk integrity checks using fsck. The "1" states that it should be backed up when the dump command is issued (0=no). The "2" refers to the order in which "fsck" should check the mount points. The digit "1" identifies the root ("/") of the filesystem. All others should be "2". (0=no check)


IF we encounter any issues in booting system after editing fstab

After entering root password
mount -n -o remount,rw /
then we can edit fstab file..
 

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