From: Gotfryd Smolik, VMS lists [gotfryd@stanpol.com.pl]
Sent: Monday, April 23, 2001 11:01 AM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: Missing 000000.dir

On 19 Apr 2001, Dave Greenwood wrote:

+We have a (virtual) disk that's apparently missing 000000.dir:
+
+  $ dir vda3:[000000]
+  %DIRECT-E-OPENIN, error opening VDA3:[000000]*.*;* as input
+  -RMS-E-DNF, directory not found
+  -SYSTEM-W-NOSUCHFILE, no such file
+
+We're using VMS 7.2-1 AXP with Glenn Everhart's vddriver, although
+I don't think either are at issue here.  (The disk is nfs-served
+to a Unix system and there was an attempt to backup/restore the
+disk using Unix-based software - it seems safe to say *that*
+caused the problem.  It's a long story and I think we can say that
+it won't happen again.  Sigh.)
+
+Since I can still do DIR VDA3:[*] and get listings of files in
+top-level directories I think we can use BACKUP to save the files,
+re-INIT the disk and then restore from the backup save set.  What
+I'm curious about is whether there's a way to recreate the missing
+000000.dir without the backup-init-restore sequence.  Anyone have
+any suggestions?

 Yes: you have missed the backlink of file named 000000.DIR  :)
 *Probably* creating properly /ENTERed link will resolve the problem.
 Do:
*WARNING* - be sure the filesystem is not used by other propesses.
 Operation on directory thru RMS is *not* supported.
 You may mount the device privetely to operate on the directories !
 Be aware the fact, that you can this way corrupt the dirfile(s)
and if you filesystem is already corrupted you can get to worse
problems. You are warned :)

$ CREATE/DIRECTORY the_disk:[TMP.TMP]

 You can use any directory name in place on TMP. It is expected,
that in the directory does *not* exist a 000000.DIR file before.
 The work is simplest (and next steps applies only to the example)
if the [TMP.TMP] dir doesn't exist before or was empty.
 You can READ and skip unneccesary records but that is overkill.

$ OPEN/READ/SHARE=WRITE IN any_other_good_disk:[000000]000000.DIR

 Althought it *is* unsupported opening the dirfile, can't see
any reason for problem. You already can OPEN a 000000.DIR on
other unused disk, with VDDRIVER that is not a problem for you.

$ READ/NOLOCK IN DIRREC
$ SHOW SYMBOL DIRREC

 Probably the first match will have the 000000.DIR in it; but *is*
possible that you have dir named b.ex. 00.DIR (means "[00]") or
a file starting with "-" etc. - then you must check if the
record is for 000000.DIR
 At end
$ CLOSE IN

 Of course, you *can* create the symbol manually:

$ DIRREC="1234000000.DIR12345678"
$ DIRREC[0,   32]=%x0A000001
$ DIRREC[14*8,32]=%x00040001
$ DIRREC[18*8,32]=%x00000004
$ SHOW SYMBOL DIRREC

(sure, the values are from real directory; that is much faster
 than manual calculation :) !)

$ OPEN/READ/WRITE IO the_disk:[TMP]TMP.DIR ! Unsupported, but allowed
$ READ IO DIRREC

 Ignore the error :)
 That way you position the record in file ;)

$ WRITE IO DIRREC
$ CLOSE IO

 You can check, if:

$ DIR [TMP.TMP.000000]

 allows you "see" all files :)
 And that *is* the proper directory !

 What wrong ?
 Still the backlink of 000000.DIR - probably is set to
the TMP.DIR :] Haven't check if ANAL/DISK/REPAIR checks
for that, probably not.
[step 2]
++++++++++++++++++++++
 Also you haven't the "root" set themself:

$ SET FILE [TMP.TMP]000000.DIR/ENTER=[TMP.TMP.000000]

 You probably will "see" the "proper root":
$ DIR [000000]

 and can remove the unneded entry:
$ SET FILE [TMP.TMP]000000.DIR;/REMOVE
++++++++++++++++++++++

 The backlink *still* is wrong. *Probably* setting second
entry in "step 2" rather than before as:
[step 2, version b]
++++++++++++++++++++++
$ SET FILE [TMP.TMP]000000.DIR/ENTER=[TMP.000000]

 and a:
$ RENAME [TMP]000000.DIR [TMP.TMP.000000]
 will correct the backlink; haven't check, but all
looks as expected.
++++++++++++++++++++++
 Of course, the reason of my description is simple: years
ago have "make visible" the fact, that ODS filesystem doesn't
themself rely of the directory structure :), in one of
steps have remove the 000000.DIR "loop" entry.

 Even if the steps before are simple, someone may say that
it is not worth do it. But for fun... and experience... :)
 Some variation (.ex. creating the [TMP.TMP.000000] with
CREATE/DIR and update FID with READ + WRITE/UPDATE) possible.

 Excuse for eventuall bugs and re-check: have check only
some steps, mistyping possible, correction welcome... !

+Thanks,
+Dave

 Regards - Gotfryd

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