Is it possible to restore a tape that was relabelled by mistake?

[StefanS]

Scenario:

A full tape of backed-up data was relabelled by mistake.

Is it possible to bring the tape (and its data) back in to the system again, like it was previously?

Regards

Stefan

 

[bigkatt]

StefanS,
I am thinking scanner is your friend. Scanner reads NetWorker media to confirm the contents of a volume, to extract a save set or rebuild the NetWorker online indexes.

BK

 

[gazza1969]

scanner will not help if you have re-labelled the tape.
Once the header has been overwritten that is it, Unless you want to take it to a DR specialist.

 

[bigkatt]

gazza1969,
I beg to differ. I could be wrong but myself and the rest of our backup team sat down to discuss this problem that StefanS is having and we think that you can run scanner to rebuild the media information. You might be able to use the mt command to skip over the lable and then try and run scanner. At this point in time if I were StefanS I would give it a shot. This is a very interesting situation. It might be interesting to send this to legato but I am sure they have no clue.
My question to you is, do you think all the data on the tape has been erased?

BK

 

[gazza1969]

I totally agree that the data is still physically on the tape, however when dlt drive labels a tape it lays down a track marker which it needs to find in order to become "ready", every time you label a tape you put down a new track marker in a slightly different place on the tape, as long as the label operation has not gone over the beginning of the data you could well recover the data, however I would not hold out much hope, I know their are data recovery services available to recover data off of tapes and disks that have been relabelled but even eith their help you are not garenteed to get 100% of your data back. scanner may well and I hope it does recover the data although as I said earlier I do not hold out much hope.

 

[StefanS]

Thanks for all your information in this matter.
If I can find the time I will test your ideas and
post the results. However I'm now stuck with a much
more urgent Networker problem. Your knowledge would
be greatly appreciated also in this new matter (se new
thread "Networker and autochanger weirdness...&quot.

Best Regards,

StefanS

 

[Guest_imported]

Please dont test these ideas. If the tape is relabeled then there is NO DATA ON THE TAPE. Remember; all that SCANNER does is recreate the CFI database for data on the tape... not read a tape that has been delete permanently!! Relabelling a tape with any piece of software deletes the BOF and EOF markers and its all gone...

 

[rgzimmer]

LGTOman is correct. Don't waste your time trying to restore data that isn't there. Only a DR specialist will be able to recover the data and that will not only be costly, but takes quite a while.

You have to ask yourself if you can do without this data or not because, from what I understand, this service is EXTREMELY expensive.

 

[gdc2001]

The Gents are correct, the only way to recover the data is to use a DR company...

 

[wallace88]

I agree that the only way to recover the tape once relabeled is to go to a DR specialist.

Just as a side note, when you relabel the tape, the information is still there. The label process simply puts in a new label, then an end of informaiton marker. The data that is after that point is still there, which is why DR specialists can go past that point and read and recover the data.

scanner won't help because, like most other regular tape reader programs, they will stop and the end of information marker.

 

[Chapter11]

I'll put in my own confirmation: it's not possible to recover the data with Networker. You'll have to use a DR company.

I've tried many many tricks with dd and directly hacking the volume header, all of which have failed.