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How to recover data in tar format from a PCS Cadmus tape

By Julian H. Stacey a computer consultant

To a question in German:
hat einer von Euch die Möglichkeit alte aber lesbare QIC-525 Bänder im (MUNIX-)tar-Format auf CD-ROM, DVD oder USB-Stick unter beliebigem MS-Windows zu bringen?
(English short equivalent approx. :~ How to read old Tar tapes. )

Here's an answer in English copied here to help others doing similar old data recovery.

( Falls jemand will dass {tech. Teil} in Deutsch lesen ... Cut & Paste via
I have a Cadmus CTS3 320/525MB drive, SCSI, not in a PC, & various PC SCSI cards & cables, used with FreeBSD PCs (& NetBSD on PC532). It reads PCS QIC-45 M & 60M PCS tapes as well as 150 & 525)

Tar formats have varied over time. Is your [dd type] blocking factor known ? Maybe your .tar were also compressed ?

Best break the work into bits:

Read the tapes on to a free Unix eg a BSD or a Linux, probably with dd. (BSD & Linux have ~ 32,517 @ 2020-08-24 + free source tools if you later need tools to convert & test etc.

Once data is on disk its safe. Repeated failed read attempts trying tar formats might test old tapes more than you want ! (I once had Very bad experiences with a load of 20 Meg CS 600 cassettes of East German manufacture: Media flaked off lots of tapes. OK that was not QIC & not a decent manufacturer. ) I wrote a program to recover tape data:

Determine if a compressor was used too, & which. I have an ancient compress.c somewhere I guess.

Experiment on a Unix to see if any of eg BSD GNU Linux tars, current or old might work (I also have source for BSD-Lite2 or so tar, & maybe some other old tars, possibly Minix & Mach etc or on net.

If you extract with PCS native tar (or indeed some old BSD tars, & probably MS tars) if tree was deep, & tape was written with FSF gnu tar (eg as available for Cadmus at least in PCS development dept) you would lose deep paths & possibly files.

If you get desperate for a genuine Cadmus hardware, ask Hans Franke of **, who might have one, or know of one.

From Unix (eg a BSD or Linux PC) list the directory structure, inc files, hard links, symbolic links, files that may have same name in upper & lower case (that may collide on DOS FS) & consider filenames that may be lost, duplicated or scrambled if you write out to whatever MS FS format you want (eg DOS FS & NTFS naming limitations )

Write out data on to media & in format of your choice. eg to CD, or FAT FS or NTFS on USB stick or tar image within DOS FS on stick.

BTW Various tar.exe have been available for MS for ~ 20+ years, a friend downloaded & ran one just last week. URLs: I wouldn't expect it to control a drive to read old CADMUS tapes though (& I'd be surprised if it could read old Cadmus images )

Falls HP.COM braucht hilfe damit, ich bin Freiberufler 089 .........

PS ** Ubrigens, Jahrliche Austellung VCFE1. bis 3. Mai 2015 in Muenchen. Alte kisten & interessante Vortraege, & einem kleine Biergarten drausen, nicht so wie Michaeligarten, aber OK.

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