Action

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 filesystem involved; if not, try to back up the filesystem now using ufsdump(1M). Then run the format(1M) command, select the disk involved, and print out the partition information.

# format : N > partition > print

Note whether the overlap occurs at the beginning or end of the filesystem involved. Then run newfs(1M) with the -N option to print out the filesystem 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