🚀 go-pugleaf

From: <engvax!ymir!4CCVAX..ANDY@cit-vax.ARPA>

Here is the error manual text for an error we got when attempting to mount
one of our disks. The disk had gotten slightly scrambled after a momentary
power fluctuation:

>       BADRCT, Replacement and Caching Table unrecoverable I/O error
>
>            Facility:  SYSTEM, VAX/VMS System Services
>
>            Explanation:  The Replacement and Caching Table is
>            unreadable or invalid.  This message applies only to
>            devices governed by the Mass Storage Control Protocol
>            (MSCP).  This message could indicate that the read
>            mechanism on the disk is defective or that the data on the
>            disk is corrupted.
>
>            User Action:  Try to copy user data from this volume to a
>            new volume.  If this fails, contact DIGITAL field service.

Note that when this happens, the disk cannot even be mounted /FOREIGN.

What the manual fails to suggest is to try mounting the disk *WITH THE DRIVE
WRITE PROTected* (not just MOUNT /NOWRITE). We found almost by accident that
(in our case) this resulted in a completely readable disk. We BACKUPed the
files to tape and then ran the disk formatter (after trying INIT which did not
work). The files were restored and everything seems to be fine now. 

Note again the crucial step was to push the WRITE PROT button on the drive.
Evidently this causes the drive logic to be less fussy about the state of
its private storage areas on the disk.

Andy Davenport
Harvey Mudd College