[comp.os.vms] ACP HEADERFULL error

nagy%43198.hepnet@LBL.ARPA (04/24/87)

According to my System Messages manual, plus an understanding of the ODS-2
file structure, I interpret this error as follows:

	- Index file is currently full

	- User is creating a new filee (result of edit, etc.) and so the
	  index file must be extended.

	- Now, one of two things is happening:

		(a) The index file extension chunk can't be allocated because
		    there is no free chunk big enough on the disk.

		OR

		(b) The index file has its own file header, this file contains
		    the map pointers for the index file (obviously).  As I
		    remember, a normal file header has room to map 7 separate
		    file extents.  I also remember that the index file CANNOT
		    be mapped with an extension header; the entire index file
		    must be described by a single file header.

The System Messages manual states that the solution is to compress the disk
with a BACKUP save/restore cycle.  When you do the restore, BACKUP will
initialize the disk and create a new Index file which is big enough to
contain all the existing file headers originally on the disk as a single
chunk of disk space.

JCV@CERNVM.BITNET.UUCP (04/30/87)

I have the impression that all the explanations to the ACP HEADERFULL message
have been wrong somewhere or other. So, to summarize:

The volume INDEXF.SYS contains three parts:

 -  home blocks and other misc. information
 -  indexfile bit map
 -  file headers

The indexfile bitmap indicates which file header blocks are in use. It is
at the beginning of the index file. Its size is specified (or defaulted)
when the volume is initialized and may  o n l y  be changed by re-initializing
the volume. It effectively specifies how large the index file may become.
See HELP INIT DEVICE /MAX_FILES for further information.
(BTW, actual initial allocation for the index file is specified via /HEADER.)

So, what the message wants to say is: No more file header blocks are free
in the index file.
The reasons are:
 -  Too many files
 -  A large number of files require extension header(s) because of:
     -  disk freagmentation or/and
     -  large ACLs

In other cases (device full and index file too fragmented) you will see other
error messages.

The remedy proposed is correct, of course: Restore the disk from BACKUP.
If the reason for the error is that you have too many files, be sure to
initialize the disk with a larger /MAX_FILES and do the restore BACKUP/NOINIT!


  --- Jan Vorbrueggen