how to "unlabel" a tape ?

Fist off, I am assuming you are talking about the Networker 'electronic' label, not the physical one.

Second,  make sure you unmount all other tapes as it's easy to make a mistake when you have to use device scsi addresses to specify the drive using either the NW erase command or the linux commands I mention below.

Third, if you do not have proper priviledges on the system hooked to the tape library storage node, you will need help from your system admin.

Although I have never tried it, there is apparently a networker erase command on both linux/unix and windows, but make sure you are running that particular one on the jukebox node machine as there may be other such commands on both unix and windows. See:

http://www.backupcentral.com/wiki/index.php/How_do_I_erase_a_tape%3F

BTW, a degausser is not what you want, all you need to do is erase the Networker label, not the whole tape.

This erase command may take a long time. If you happen to be running your jukebox on a unix or linux machine, you (as admin or root) could use tar or dd to wipe out just the label after loading the tape in the drive with networker.

If this is a windows machine, there may be other solutions. I'd just google 'windows tape erase' and find it that way. I googled 'networker label erase' to answer this question BTW.  

eivinda wrote: Hi I need to test the auto media management feature on new unlabeled tapes. My problem is that I do not have any tapes without a label. My question: Can I "unlabel" a tape to make NetWorker think it is a new tape without a label?

You can delete tape from mdb and it will be seen as unlabeled and subject of AMM (eg, nsrmm -dy VOLUME_NAME)

There are 2 issues:

  -  Make sure that the volume (and all save sets) have been deleted from the media index.

  -  Then insert the tape into a device and run NW's "tapeexer(cise)" command.

          This is the fasted method to overwrite the label and loosing all other information.

"Erase" will work. However it is nothing else but the SCSI 'Security Erase' command which erases the whole media (from the current position or from BOT). As mentioned already, it may tape hours depending on the media type.

Hi,

I think you can use the nsrmm -d as mentioned by Hrvoje in earlier reply , but as far as i know that deleting the volume will result a message "tape is not in media index" ,and here there is a difference between tapes that are unlabeled (means no Networker label can be found - for example using brand new tapes or tapes overwritten with a different backup software) and tapes that are 'not in media index' (means they have a Networker label and has been deleted). Networker does not use tapes marked as 'not in media index' for automatic re-labeling operations when auto-media-management is enabled. Unlabeled tapes are used in this case. I didnt try it by myself, but it worth a try and look for the NetWorker behavior after deleting the label, will auto media management recognize it as a new volume and re-label it or not.

Waitng your updates.

Ahmed Bahaa

Hi Ahmed,

what i meant is that you should delete the entries in the MI (nsrmm -d volume) before you overwrite the tape. However, NW's tape test utilities do not write a NW label - they do not even verify if one exists. So be carful and do not use valid tape!

But i am also sure that NW's AMM will not overwrite any unknown NW tape as it can not verify whether the data is still valid.

Ida Socca wrote: But i am also sure that NW's AMM will not overwrite any unknown NW tape as it can not verify whether the data is still valid.

When did that change?  In old days that was main reason not to use AMM - it would take literally any tape unknown (and it would not matter if old NW label was found - given that is not part of current mdb).

All,

I am not aware of the behaviour suggested by AAM by Hrvoje. As far as I know AAM has never labelled a volume which has a NetWorker label on it which was not in the Media Database (MDB). The logic behind this was you could have multiple datazones and accidentally put some tapes from one datazone into a jukebox for another. NetWorker was "intelligent" enough (not a phrase commonly used by Customer!) to see this volume may either be required by itself (i.e. accidentally deleted from its MDB) or could belong to another NetWorker server and also still be valid.

Once a volume has a NetWorker label on it the only way I know to get AAM to label this volume again was to overwrite the NetWorker label (which equates to the first 128Kb of the tape as label consists of 2 x 64Kb block). This can be done using any OS tape write command (i.e. tar on Unix) and writing something to the volume which is equal to or greater than 128Kb. Once this was done the volume would then be treated as a scratch or unlabelled volume and could be labelled.

PLEASE NOTE: There is no way to recover the NetWorker label or other data on the volume once this is done. You do not have to overwrite the full tape but once the first 128Kb is overwritten the rest of the data is useless to NetWorker and cannot be recovered, so ensuring you are taking actions on the correct volume is essential. As previously suggested I would advise having only one volume loaded in any tape drives when this procedure is done to ensure you do not overwrite on the incorrect volume.

Regards,

Bill Mason

Bill,

let me give a 'heads up' for all these guys who have accidentally labeled a tape. The data is not necessarily lost - you can just not access it with standard OS/NW tools. The reason is that the drive's firmware does not allow you to pass the logical-end-of-tape (LEOT). 

If you are willing to forget about the starting section (the first save set(s)), you can even try to fix it this yourself.

I have successfully done this years ago on a DLT7000 media but have never tested this again since.

In general, this is the procedure:

  - use a standalone device

  - start writing a new backup

  - as soon as you hear the drive streaming, switch of power - the brutal way but of course this may happen.

    Because of that, the tape drive can not write a double filemark which indicates the logical-end-of-tape (LEOT).

  - next switch on power and try to scan the tape.

    It may take a while until NW finds the a new save stream but then it will 'resync' and should be able to scan the rest.

Yes, of course it is a dangerous method - you could even delete more data that you want to loose. But it should still work.

For all the others which still need all data, ask a data recovery company like Kroll Ontrack - they have more sophisticated methods. But they can fail as well.