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口令丢失，但光盘启动时无法mount
How to Restoring a Bad Superblock---------------------------------------------
When the superblock of a file system becomes damaged, you must restore it. fsck tells you when a superblock is bad. ortunately, redundant copies of the superblock are stored within a file system. You can use fsck -o b to replace the superblock with one of the copies.
How to Restore a Bad Superblock
1. Become superuser.
2. Change to a directory outside the damaged file system.
3. Unmount the file system.
# umount mount-point
Caution - Be sure to use the newfs -N in the next step. If you omit the -N option,
you will create a new, empty file system.
4. Display the superblock values with the newfs -N command.
# newfs -N /dev/rdsk/device-name
The output of this command displays the block numbers that were used for the
superblock copies when newfs created the file system, unless the file system was
created with special parameters. See “Deciding on Custom File System
Parameters” on page 542 for information on creating a customized file system.
5. Provide an alternative superblock with the fsck command.
# fsck -F ufs -o b=block-number /dev/rdsk/device-name
fsck uses the alternative superblock you specify to restore the primary
superblock. You can always try 32 as an alternative block, or use any of the
alternative blocks shown by newfs -N.
Example—Restoring a Bad Superblock
The following example restores the superblock copy 5264 for the /files7 file
system:
# cd /
# umount /files7
# newfs -N /dev/rdsk/c0t3d0s7
/dev/rdsk/c0t3d0s7: 163944 sectors in 506 cylinders of 9 tracks, 36 sectors
83.9MB in 32 cyl groups (16 c/g, 2.65MB/g, 1216 i/g)
super-block backups (for fsck -b #) at:
32, 5264, 10496, 15728, 20960, 26192, 31424, 36656, 41888,
47120, 52352, 57584, 62816, 68048, 73280, 78512, 82976, 88208,
93440, 98672, 103904, 109136, 114368, 119600, 124832, 130064, 135296,
140528, 145760, 150992, 156224, 161456,
# fsck -F ufs -o b=5264 /dev/rdsk/c0t3d0s7
Alternate superblock location: 5264.
** /dev/rdsk/c0t3d0s7
** Last Mounted on
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
36 files, 867 used, 75712 free (16 frags, 9462 blocks, 0.0% fragmentation)
/dev/rdsk/c0t3d0s7 FILE SYSTEM STATE SET TO OKAY
***** FILE SYSTEM WAS MODIFIED *****
#
If the superblock in the root (/) file system becomes damaged and you cannot boot
the system, reinstall /kernel/unix and rebuild the root (/) file system with newfs.
Checking File System Integrity 523
Because a superblock is created by the newfs command, you do not need to restore it . |
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发表于 2004-12-31 10:38
