11 March 1987

	After RESTORE.EXE has successfully restored a file header the file 
header is protected from re-use. However the data blocks are not protected
and may be re-used. The VMS ANALYZE/DISK_STRUCTURE is used to mark the data
blocks as being used by the file and so protect them from re-use, it is also
used to put the file back into a directory so it can be accessed in the 
normal way.

	ANALYZE/DISK_STRUCTURE should only be run to repair the disk (ie. 
using the /REPAIR qualifier) when all the file's headers have been
processed by RESTORE as ANALYZE/DISK gets confused and you may end up with 
only that part of the file described by the processed headers rather than 
all of it.

	Note the documentation "VAX/VMS Verify Utility Reference Manual"
(VAX/VMS version 4.0) says "You should not execute the Verify Utility on a 
disk that has concurrent file activity; such use of the utility can result
in spurious messages that incorrectly indicate severe file damage", VER-2.
However ignoring this advice has not caused any problems, provided errors
reported for files that are active are ignored. However there will be a 
severe performance problem if you use the /CONFIRM switch and go to lunch!
(the users should have gone for lunch as well).

	The documentation on GETFILE.COM says it should have exclusive access
to the disk because it is considered prudent (rather than essential) for
there to be no file creation or extension activity whilst RESTORE is 
operating. This is because both activities may attempt to grab file headers
whilst RESTORE is modifying [000000]INDEXF.SYS but there is no syncronisation
between them and RESTORE. ANALYZE/DISK can be used to tidying up any problems
caused. It is as well to prevent file creation and extension as soon as
possible any way as another file may grab and then overwrite data blocks from
the file(s) you are attempting to recover.

	If RESTORE is run but no file headers are restored then it makes no 
changes to the file system and so can be run at any time. It may be useful to
scan the disk first to see if the file(s) can be found before shuting down 
file activity on it. Note RESTORE processes only file headers that have been
deleted and so will ignore files which are simply 'lost'.

I hope this is helpful.

	W. B. Langdon