The most common cause of this error is overlapping disk partitions. Do not immediately rerun fsck(1M) as suggested by the lines that display after
the error message. First, make sure that you have a recent backup of the file system involved; if not, try to back up the file system now using ufsdump(1M).
Then, run the format(1M) command, select the disk involved, and print out the partition information.
Note whether the overlap occurs at the beginning or end of the file system involved. Then, run newfs(1M)
with the -N
option to print out the file system parameters, including the location of backup super blocks.
# newfs -N /dev/dsk/device
Select a super block from a non-overlapping area of the disk, but note that in most cases you have only one chance to select the proper replacement
super block, which fsck(1M)
soon propagates to all the cylinders. If you select the wrong replacement super block, data corruption will probably occur,
and you will have to restore from backup tapes. After you select a new super block, provide fsck(1M)
with the new master super block number:
# fsck -o b=NNNN /dev/dsk/device