    AST RESEARCH, INC.         TECHNICAL BULLETIN #0874               10-11-93

                 CO UNIX fsck(ADM) COMMAND AND AST COMPUTER SYSTEMS

    PROBLEM:       The message "FREE BLK COUNT WRONG IN SUPERBLK" is encountered
                   when executing the fsck command on the root filesystem.

    SYSTEMS
    AFFECTED:      All AST computer systems using SCO UNIX or SCO ODT operating
                   systems.

    CAUSE:         The root filesystem is mounted when the fsck command is
                   executed.

    SOLUTION:      Boot from the Emergency Boot Floppy set and execute fsck on
                   the root filesystem.  (Reference SCO's Installation Guide for
                   more information regarding creating an Emergency Boot Floppy
                   set)

                   If the floppy set isn't available, customers have reported
                   that synching the cache and disk filesystem structures three
                   times immediately prior to executing fsck often results in
                   fsck executing without errors.  For example:

                   1.   Enter single-user mode
                   2.   sync;sync;sync;fsck -b /dev/root

    NOTE:  Erroneous errors can be reported any time fsck is executed on a
           mounted filesystem, including incorrect free block count, incorrect
           free inode count, lost inodes, etc.  This is because the UNIX
           filesystem keeps in-memory caches of filesystem structures, but fsck
           reads the filesystem directly from the disk.  It is normal for the in-
           memory and on-disk filesystem structures to be slightly out of sync.