Erasing Backup Image in VTL

[raj08]

Hello All,

Is it possible to erase a Backup_Image in a VTL manually?

Thanks,

RAJ

[Marianne]

Backup image needs to be expired before tape can be erased.

What exactly do you need to do? Is this question related to your other post https://www-secure.symantec.com/connect/forums/scratch-tapes-and-quick-erase-vtl ?

[Genericus]

VTL emulates tape, it really is the same process, unless you have some additional stuff going on.

Expire the tape image, and return it to scratch.

Of course - since NetBackup does not return the tape to scratch until all images are expired, if this is not the last image on the tape, the data will still be there until all are expired.

If you absolutely MUST validate the data is gone, you should copy every OTHER image to another tape and then expire the tape and reformat it, or overwrite it.

This is another reason why you should never mix retentions on a tape.

[revarooo]

>> Of course - since NetBackup does not return the tape to scratch until all images are expired, if this is not the last image on the tape, the data will still be there until all are expired.

Actually the data is still there until all the images expired and the tape is re-used and overwritten rather than just expired, but technically you are half right :)

[raj08]

Hi Marianne. No, this is not related to my other question. I didn't want any confusion with that. Hence I posted as a new question. :) I will try my question in a different way.

If I believe we have duplicate image of particular server (not technically) due to some additional entry in multiple polices. (Technically this is not a duplciate image but as we have additional entry of same server in many policies, This is Duplicate). And now I have removed the server entry in additional policies and kept only one.

Now, my question is, we have many backup images due to those additional entry in VTL which we actually dont need but those are occupying space. Hence I asked, Is it possible to erase only a particular Backup_Image (not a tape) in a VTL so that I can gain some space.

P.S: Here I dont care about the exact expiry date of Media or the Image. I just want to delete the image.

Thanks,

RAJ

[Marianne]

If your VTL was normal disk storage instead, it would be possible. 
With DSU, expiration of a single image will also delete that image from disk.

Because VTL presents itself as tape, this is not possible. Space taken up by expired images cannot be reclaimed. All images on a tape must expire before tape can be overwritten from the beginning.

Please not that NBU does not erase tapes when images expire - tapes are simply available to be overwritten.

See this blog : https://www-secure.symantec.com/connect/blogs/understanding-how-netbackup-writes-tape

[raj08]

Sorry, I am missing something here. Yes, our VTL is a normal disk storage and it also presents itself as Tapes. So you mean to say that it is now possible to erase a image.

You haev mentioned something like "With DSU, expiration of a single image will also delete that image from disk.". Would you be able to explain it briefly to me? Kindly bear with me. I am just trying to understand the whole concept as I am new to this technology. Thank you.

[Marianne · Accepted solution]

No. When VTL is presented to OS and backup application as TAPE, it is treated as such. VTL is added as Media Manager Storage Unit. Virtual Media is treated same as physical tape. All the rules for physical tape applies to VTL. Neither the OS nor NBU knows that VTL is actually disk. 

VTL does not present itself as DISK, therefore it cannot be added as Disk Storage Unit using an OS mount point or drive letter. It does not have a filesystem that allows for Random Access so that individual images can be delete...

Expired VTL images are not erased because they are on TAPE. The fact that it's vitual tape makes no difference.

So, the answer is NO. Expired images cannot be deleted from (virtual) tape.

See the blog in my previous post for the rules that apply to tape - physical and virtual.

Please also see this White Paper: 

Using Virtual Tape Libraries with Veritas NetBackup™ Software

[raj08]

Thanks Marianne. Thanks for you time in explaing in details. Appreciate that.

[Jim-90]

You have to relabel tapes to blow everything away and free up space on the VTL.  Some VTLs are aware of expired images and will delete them.