corrupt label - wrong magic number or corrupt label or corrupt label - label checksum failed

Cause

After a power cycle, the machine displays either of the following error messages:

• corrupt label - label checksum failed

• corrupt label - wrong magic number

  0 unassigned    wm       0               0         (0/0/0)          0
  1 unassigned    wm       0               0         (0/0/0)          0
  2     backup    wm       0 - 5460        4.2G    (5460/0/0)   4154160
  3 unassigned    wm       0               0         (0/0/0)          0
  4 unassigned    wm       0               0         (0/0/0)          0
  5 unassigned    wm       0               0         (0/0/0)          0
  6 unassigned    wm       0 - 2730       2.1G       (0/0/0)          0
  7 unassigned 	  wm       2730-5460      2.1G       (0/0/0)          0

The disks were using raw partitions beginning at block 0 (cylinder 0). The disk label (VTOC) is kept on the block 0 of cylinder 0. The label eventually gets overwritten by database programs using raw partitions, if the raw partition begins at cylinder 0. (UNIX® file systems avoid this area of the partition.)

Action

As a workaround, do the following:

1. Go into format(1M) and get the backup label using the backup command.

2. Relabel the disk using this backup label. You should then be able to access the disk.

3. Backup the data on this disk.

4. Go back to the disk and relabel it, starting the raw partition at cylinder 1. (This loses one cylinder, but prevents corrupting the VTOC.)

5. Label again.

6. Restore the data from your backup.