[Simh] Reading VMS Backup tapes on Linux

[Stephen Hoffman]

On 6 Apr 2012 13:35:50 -0700, Sean O'Banion posited:

> "Direct-access tape support": do you have any suggestions on a USB to SCSi adapter that I might try testing my TZ30 tape drive on my Mac Mini (Intel) under OS X 10.6.8?  Not that I think I can get to it soon (some employment is needed...), but so I can look for hardware that might serve the purpose.

Thank you for your offer.   

I don't have any USB-to-SCSI adapters I'd suggest.  

Most of the SCSI storage hardware is getting stale and is getting replaced, and those adapters are getting scarce.

As for vmsbackup, I've received no feedback around the tape direct-access features.  None.  Various fixes for bugs certainly (and gratefully) received, but not in the tape path.

There's an alternative to debugging the tape and related operations on random tape devices and random OS platforms.  Simply dd'ing the data into a tape image on disk, and then running that image through one of the existing virtual tape driver packages, or using some "simple" tools to pull the saveset out from among the various ANSI tape records.  Both would seem far more maintainable approaches, too.  (And this assumes that the vmsbackup code doesn't still work.)

Given both the lack of interest in this tape access support from (the few?) vmsbackup users, and given the available access to VMS servers here in the 'labs, this vmsbackup work has been less interesting than some of the other open-source programming that's underway here.

If you're looking for a project to assist with, then Mr Elson might be interested in some assistance with his virtual tape project.  It might also be useful to provide some documentation and/or testing of one of the other virtual tape packages that are around.  Or (as Bill Peterson was asking recently over in comp.os.vms) creating some documentation around how the new OpenVMS hobbyists can use the "new" hobbyist disk images, such as how to download and unpack those for use with simh.  And certainly if you're interested in (testing, implementing, updating) the vmsbackup tape support, then I can forward along the most recent source bits.  There are more than a few projects around.

And FWIW, the RESET_BACKUP_SAVESET_ATTRIBUTES.COM tool has been on the OpenVMS Freeware distributions for a number of versions, in the 000TOOLS area.  The BACKUP headers are actually sort-of kind-of documented in the OpenVMS definitions and related materials.  Those BACKUP-related data structure definitions were included (albeit in a weird spot) in recent OpenVMS installations.  And for completeness, OpenVMS V8.4 has the BACKUP /REPAIR qualifier.


Stephen Hoffman  -  HoffmanLabs LLC