I meant to restore some files, but I forgot that there was a monday backup job just waiting for tape loading.

So veritas 10d started to write over my tape and that valuable data is now gone.

The original data size was about 40 GB and that accidentally started job wrote about 30 MB to the begin of tape.

What are my possibilities to recover some data from that tape?


Inventory and catalog doesn't help, media settings are overwrite, not append. It is a DLT drive.


Inventory and Catalog it and see if any of the data shows up in the selection list for a restore job.


It depends -- many tapes have a sort of a filesystem on them that contains a table of contents and an offset to each specific file on the tape. On AIT tapes it is actually flash media in the tape itself called MIC.

If netbackup zeroed out the tape then the it will have had the number of files on it and their offsets wrong relative to the data you actually want to restore. For instance -- this is a tool that says it recovers an ait tape from the sort of situation you're in right now. I've never used it but it sort of illustrates the situation you're in.

If the data is really important, you may want to stop messing with the tape and send it to a facility that specializes in this sort of thing before things get worse. This is likely a common situation so it is likely that if there is anything to recover they will find it and recover it (and quickly)

Lastly, depending on the type of tape and tape drive -- serpentine or helical, you may have either randomly corrupted your data or only corrupted the first bit of it. I'm not sure if modern DLT tapes have a different erase head but it is possible that random chunks of the data have been erased by starting at the head of the tape.


I'm sorry to say that only the manufacturer may be able to recover some data. May be !

Tape drive is known as sequential data support.

The quickest way to erase a media is to write at the begining of the tape, because at the end of the write or write FileMark, the drive writes a special marker named "End Of Data".

I never saw any special instruction available to SCSI level which permits to read past this "End Of Data".

So simply put, your tape has been erased at the very moment the first byte were write at the begining of the tape.

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