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Unable to read entire TK50 tape - Suggestions needed.

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abrsvc
Respected Contributor

Unable to read entire TK50 tape - Suggestions needed.

I have attempted to read an older TK50 tape without much success. The tape is an older backup tape and contains some sources that are needed. The backup begins and reaches about 1/3 the way throught the tape then a controller error occurs. I am using a TZ87 drive and all the lights on the right hand side blink repeatedly.

Note:
1) I have attempted this with 3 different drives thus far with the same result.

2) Once the tape gets into this condition, I need to manually remove the tape and rewind it into the cartridge. No amount of power cycling or resets of any nature will rewind or unload the tape.


Any suggestions?

Thanks,
Dan
16 REPLIES
Hoff
Honored Contributor
Solution

Re: Unable to read entire TK50 tape - Suggestions needed.

If one or more of these drives is a TZ87 and these are not all TZ87N series drives, then I'd suggest ceasing recovery efforts as that just scrapes off more of that limited resource of readable bits of oxide, and calling upon a data recovery service.
Jan van den Ende
Honored Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

Dan,

Way back we regularly had similar issues.

If turned out, that reading such tapes with a non-SCSI drive regularly succeeded (with a number of "recoverable media errors").
SCSI however is unable to proceed past a single parity error.
( That is why we used to say that SCSI was pronounced like the Italian Scusi "I am so sorry" -- for the poor quality.
But SCSI was less than 10% the cost of solid DEC-style periferals, so ....

_IF_ you can sill find and operational TK50 or TK70 drive, you stand a fair chance. You WILL need patience! But NO way I can guarantee success. Just as Hoff said: it is already old stuff, and the repeated tries have done nothing to improve them!

Proost.

Have one on me.

jpe

Don't rust yours pelled jacker to fine doll missed aches.
abrsvc
Respected Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

I have a TK70 drive that I can install into my VAX machine that I can try. I haven't as yet because of the need to install the TK70 controller. Maybe over this long weekend, I'll try that path.

Thanks for the suggestions.

Dan
Bob Blunt
Respected Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

Dan, reading a TK50 with a TK87 is really stretching the envelope as it is. The TK70 would be much closer to native and I'd encourage you to try that. If that doesn't work I could check in the garage and see what model TK drive I have. That effort would be complicated because the host system was DSSI-based and is currently diskless.

Now if it were my data I might carefully try to fiddle around with the cartridge and make triple sure that the tape wasn't buggered inside the "can" so to speak. We used to have some bizarre experiences at a former employer where all our 40 production MicroVAXen had their reloadable personalities on TK and we never knew if the tape drive had a ton of drywall dust or a herd of dust bunnies inside the drive. Reloading was always a challenging toss-up.

If you can't get the data directly yourself we might trade contact info if your options dry up.

bob
abrsvc
Respected Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

Thanks for the updates. I have multiple TK70 drives available that can be installed in a DSSI based system (still functioning after 10 years with 2 reboots...). I'll let you know how it works out next week.

I'll be resurrecting a couple of Flamingos this week end too. Should be fun.

Dan
abrsvc
Respected Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

Any suggestions on how to remove the tape other than by dis-assembly and hand winding? The tape appears to be about 1/3 wound inside the drive.

Thanks,
Dan
Stanley F Quayle
Valued Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

I have a number of table-top TZ87 drives to do TK50/TK70 recoveries. If you remove the drive from the enclosure (I just cut a hole in the enclosure), you'll see a Phillips screw that is in-line with the center of the cartridge.

GENTLY rewind the tape (counter-clockwise as seen from the underside of the cartridge) and it will wind back up into the TK cartridge. I use a wimpy power screwdriver to do this, since it takes lots and lots of revolutions to get it all back in.
http://www.stanq.com/charon-vax.html
Stanley F Quayle
Valued Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

Call MSRC Company Inc., 603-642-6300, Brentwood NH. They can totally refurbish a TZ87 drive to like-new specs, including a new TK50 head.

My technical contact there was Matt Parker at extension 239, but it's been a few years since I spoke to him, so I don't know if he's still there.

You'll want to clean the head after each tape (or attempt). Use non-fabric cleaning wipes and isopropyl alcohol to clean the head -- you have to pull the clear (usually) shield off the inside of the drive to get to the head.

You might guess that I've spent entirely too much time inside the TZ87 hardware...

Unfortunately, if you pull a hard error on the drive, you're dead. There was some "diagnostic" firmware that would let you continue, but it was never released into the wild. Some very expensive recovery shops like OnTrack Data Recovery (http://www.ontrack.com/datarecovery/servicequote.asp?PartnerID=2337811) [yes, I'm a partner] might have that firmware. I've never asked.
http://www.stanq.com/charon-vax.html
abrsvc
Respected Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

I was a bit surprised that a power cycle did not effectively rewind the tape abck into the cartridge. I would have normally expected this to occur. I just received a number of TK87 drives that I will test. But will wait until I attempt the TK70 drive. I just found a TK50 drive as well still wrapped in the packing envelope. I will try that as well.

Thanks for the suggstions.

Dan
Jan van den Ende
Honored Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

Dan,

>>>
I just received a number of TK87 drives that I will test. But will wait until I attempt the TK70 drive. I just found a TK50 drive as well still wrapped in the packing envelope. I will try that as well.
<<<

Okay, but remember the SCSI vs DSA situation.

I have once read a 15 year old 800 BPI (!) tape
with just over 35000 (thirtyfive THOUSAND) recoverable errors. It took 0ver 4 hours, CPU bound (!), to recover a file that could be transfered to tape in about 3 minutes, but WE GOPT IT.
Multiple experience with TK50 & TK70 with > 100 recoverable errors.
A SCSI TK50 drive: ONE error is the end of it.
We held on to non-SCSI TK70 (and reel) drive drives just for such cases for many years. Definitely much slower, but we were more than ready to pay THAT price!

Ans it has already been remarkerd: clean the drive before AND AFTER each try!

Good luch (you will need some).

Proost.

Have one on me.

jpe
Don't rust yours pelled jacker to fine doll missed aches.
Stanley F Quayle
Valued Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

> I was a bit surprised that a power cycle did not effectively rewind the tape back into the cartridge.

This doesn't happen with TZ87's. At least, not on the six I have...

http://www.stanq.com/charon-vax.html
Stanley F Quayle
Valued Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

To clean those non-TZ87 tape drives, you'll need the DEC TKXX-HC cleaning kit. I found some listed on varx.com for $199...
http://www.stanq.com/charon-vax.html
Bob Blunt
Respected Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

Dan, I missed in your initial entry that the tape was stuck in the "can" so to speak. The behavior of the "brick" (the tape itself) in question depends on what the firmware has been programmed to do and there's firmware on several modules in one of those drives. The best solution, as previously mentioned, is to carefully use a powered screwdriver and rewind into the cartridge. You can (and I have, painfully) rewind using a regular screwdriver but it takes forever and your forearms will not quickly forgive you.

Leave the cartridge in the drive when you do this. My recommendation about opening the cartridge was intended just to check the tape itself for damage AFTER you have it rewound.

The power-on behavior with a partially unloaded cartridge can be strange. I've had some drives in that family that immediately sensed the tape and "promptly" wound it all onto the take-up reel inside the drive. This was usually when the MicroVAX got powered-off in a big hurry, the drive pulled and the screwdriver applied. Sometimes you can force the drive to rewind by mashing the unload button repeatedly (on the TK50/TK70 units). I haven't had great luck with the real DLT units but I also haven't had the frequency of problems I had with the original TK50s either. The old drives also had a wheel and sensor in a plastic housing that detected tape motion. Those would fill with a monster dust bunny and the sensor would fail and send the drive into weird mode. I rebuilt more than my fair share of TK drives back in the day just to get our operation back online. It can be frustrating.

bob
abrsvc
Respected Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

Update:

It would appear that the tape has some contamination on it. A slight "nudge" on the spindle released the tape and the unit was able to rewind the tape into the cartridge. The power cycle actually was attempting to move the tape, but was not able to because ofhte contamination. I don't have a clue what is on the tape that is causing this, but will investigate. I'll need to clean the tape somehow.

Stay tuned, as the saga is not yet complete...

Dan
Stanley F Quayle
Valued Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

You might search ITRC for more help, because this topic comes up from time to time.

As for cleaning the tape, there was once a non-DEC device that would clean TK50/TK70, but was discontinued years (>10) ago.

The usual problem isn't contamination of the tape, but the tape itself becomes sticky. There was an ITRC posting about baking the tape in a low-temperature oven to remove any moisture; the poster thought that humidity might be contributing to the stick problem.

http://www.stanq.com/charon-vax.html
Bob Blunt
Respected Contributor

Re: Unable to read entire TK50 tape - Suggestions needed.

Right, there was an issue with the cartridges being extremely sensitive to changes in humidity and temperature that resulted in a condition called "stiction" where the layers of wrapped tape would stick together. I think there was a Blitz that was released that cautioned about the situation and gave guidelines about how to handle it. There was a very small window of difference in humidity and temperature allowed.

There are companies who offer recovery services and address stiction issues on tapes they handle. Google returned several responses but I had to narrow down the search to find this: http://www.hp-store.com/PD_01382.aspx

I've never had a stiction problem on the early drives but that doesn't mean it wasn't happening and just not identified. I've always used the TK cleaner on the older TK50/70 and TZ30 drives and it can work some miracles. But if the media is peeled off the tape... ouch. I know that older reel-to-reel tapes could more easily fall-back on the redundancy groups for data recovery but the cartridge drives...especially DLT, DAT and 8mm in my experience...have to be specially coerced with recovery-capable firmware to even try. Hopefully with an older, non-SCSI TK drive you can get it to try harder.

bob