Ref: 21770003
Title: Explanation of NCS/AT "Possible File Size Error I=###"
Date: 4/3/91

Copyright 3Com Corporation, 1991.  All rights reserved.

When booting or performing fsck on an NCS/AT, the following error message
means that the XENIX filesystems's inode numbers may be corrupt:

   /dev/u
   Phase 1 Check Blocks
   Possible File Size Error I = ###

(### represents a two- or three-digit number.)

Inodes are pointers to files in the XENIX filesystem.  They keep track of a
file's location and other file attributes, such as file type, permissions,
owner, creation date, blocksize, etc.

The error will occur on bootup only if fsck has been added to the etc/rc
startup script before the user file system /dev/u is mounted.

To get rid of the error message and fix the inode corruption, follow these
steps:

1.  Boot the NCS/AT in maintenance mode by typing the root password instead
of Ctrl-D during bootup.

2.  Type umount <filesystem> (in this example, the filesystem is /dev/u).

3.  Type fsck -s <filesystem> to reconstruct the actual free list by
UNCONDITIONALLY rewriting the superblock of the filesystem.

Note:  An fsck -S is a conditional reconstruction; the free list is rebuilt
only if there are no discrepancies discovered in the filesystem.

4.  Type fsck -rr /dev/root to recover the root filesystem.

If there is still a problem with the inode, use the clri <filesystem>
<i-number> command, which writes zeros on the 64 bytes occupied by the inode
numbered <i-number>.  After clri is executed, any blocks in the affected file
will show up as missing if the file system is checked with fsck.

See the commands manual for further information on fsck options -s and -rr and
the clri command.

