I am relatively new to DD. I apologize if this has been asked, but I can't seem to find an answer here.
I have seen DD presented as a VTL over FC. My question is: is there any way to access the underlying "files" that make up the VTL? I am sort of assuming each virtual tape in the library is represented by an actual file in a pool or volume of some kind on the DD. Is there any way to access those underlying files and copy them on/off of the DD? Sort of like a VTL Tape export/import routine, but to file instead of to another tape. Is it possible to access the VTL files vis SCP, NFS, CIFS, FTP, anything?
It is possible, but not recommended and certainly not by design. Each tape is I believe one file if I remember correctly. To move around stuff is not allowed as you might break things so forget about it. I suspect your vtl is used by some application and if you wish to move data from one tape to another use application to do that. Beneath DD will do it quickly and both DD and application will be aware of the change.
Thanks for your help and advice. I get that it would be unsupported and not advisable - my use case is lengthy and unimportant to the discussion. Let's assume I don't have a choice: DD is my only VTL option, and I have to be able to move the virtual tapes on and off DD for something unavoidable, like a compliance policy that corporate just won't change, etc. Stick with me on "possible" if you will. I don't need the "how" right now, just consensus that it can be done.
If I understand correctly then, there are means to copy the VTL files off the DD box using some kind of file sharing based transfer? I didn't think you could share the VTL volume back out, as say CIFS?
Is there a way then to drop old "virtual tape files" (virtual tapes DD thinks you have deleted in the past) back on the DD VTL volume and get DD to recognize them as existing again? It doesn't need to be an easy process, as this is an unlikely, but possible, scenario. Even if it means something like: create a new tape in DD's index, rename the old tape file to match, and replace the newly-created empty tape? My app for backups (say BRMS on the AS400) would just need to re-index the tape then. Alternatively, If I told BRMS to re-use the virtual tapes every 90 days, I could potentially "replace" a newly written tape with the same "tape file" from years ago, which would represent a different set of data that I want to restore. Again, I'd assume BRMS needs re-index the tape. Would anything like these ideas work?
I'd plan on keeping the recent data on the DD - but if something historical MUST be restored, I have to find a way to re-import the backups, in this scenario, that corporate sent me.
Again, each tape is file and yes there is a way to get to that file if you configure your system that way. However, this would break any serious compliance so this approach has a problem in its start (apart that is not supported).
If you wish to protect tapes, you can move them (export) to vault. Also, it talking about compliance, you can get retention lock (RL status on tape). I think that requires license. If that is too much, you can always set it to RO status.
I do not know how it works on AS400 nor how BRMS works, but normally you would create pool per retention and tapes would get reused as soon as they can be reused. Backup application would have that all tapes in index all the time so there is no reason to move around tapes. Which brings me to what most likely might be your issue - space on DD where by moving you wish to free up some space. I think the file on DD contains links to data which is deduped and most likely by removing that you would end up in trouble. Even if you put it back it would not work after some time as global index would change and pointers would no longer be valid. At least I suspect so. So, if your issue is space usage, the only we out would be to copy/move data via backup application from DD tape to PTL tape. If space is not the issue, I would simply use vault and if needed retention lock as well.