My understanding of the 'LTO-4 tape in LTO-3 drive' issue is that Networker 
(through the drive) will sense an invalid tape and spit it out without 
mounting.  Has anyone tried this?

Also, if I just got all LTO-3 media (separated by pools) this would become moot 
I suppose.  Or get 4 x LTO-4 drives (probably SAS) and keep the dedicated WORM 
pools as LTO-3.

We do have another SL-48 here (/w LTO-4) that's being kitted out for a separate 
project.  I may see if we can use one LTO-4 there for local/staged copy, and 
clone to LTO-3 or LTO-2 for offsite (using the other SL-48).

--TSK

=====
Tim Kimball
http://sungak.net/
=====


-----Original Message-----
From: bingo [mailto:networker-forum AT BACKUPCENTRAL DOT COM] 
Sent: Tuesday, August 16, 2011 4:50 PM
Subject: Current state of mixed media in library?

First - Officially, a mixed media environment in a jukebox is not supported.

Second - Frank's solution will work ... but not securely enough.

The manpage/command reference for nsr_pool states for the attribute: 

devices (read/write, choice)
  This attribute lists the ONLY devices that volumes from this pool are allowed 
to be mounted onto. ... 


However, there are also operations where no mount is needed or even possible. 
Worst case in this scenario is labeling. If you let NW choose, then the media 
will end up in the wrong device with these potential consequences:

  - If an LTO3 media end in an LTO4 drive, there should not be any problem.
  - If an LTO4 media will be inserted in an LTO3 drive, the drive will not be 
able to read the media (to verify the tape label). Thus may lead to the fact 
that you might accidentally delete (overwrite) a valid LTO4 media when testing 
the media with other utilities like tapeexercise.

In fact i don't even know whether an LTO4 tape can be written by a LTO3 drive 
at all. But assuming that it is possible, you might then run into another 
problem if you insert it back into a LTO4 drive. This will now verify a tape 
written with lower density and due to firmware, it will use the density found 
which means that you will never again be able to change to the max (LTO4) 
density unless you erase the label with an unconditional overwrite like 
tapeexercise.

I have also been told that for reading processes, the drive is even 
unpredictable.


To conclude the technical facts: 
  - Make sure that you, not NW, controls the load scenarios (labeling, scanning)
  - Even then, mixed media is still not supported.

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