Balanced usage of tape drive generations. Changing behaviour of librarymanager when selecting drive for tape mount.

The idea is:
When using a specific format in a deviceclass, the tapedrives selection alogorithm should not discriminate tapedrives with higher capabilities

In an environment with different tapedrive models (for example TS1155 and TS1160) but all deviceclasses have the same specific format (for example 3592-5AC), the librarymanager should not consider the tape drive capability for decision of which drive to use.

When a TS4500 tapelibrary contains tapedrives of different generations, the librarymanager does not handle them equally.
When mixing TS1155 and TS1160 drives in the same logical library, TS1160 drives are only used when all TS1155 are in use.

The reason is the sorting method of the librarymanager when selecting a tapedrive.
On every mount request it creates a list sorted by least capable tapedrive => most capable tapedrive
The highest capable tapedrives always are at the end of the list.
(see attached file device sorting in librarymanager).

That leads to a situation where TS1155 are much more used than TS1160.
(see attached table mounts per drive per day.jpg).
We can see that 1155 drives are used 7x more than 1160.

So soon the situation is: Having a lot of worn-out 1155-drives vs. a lot of nearly unused 1160-drives.

Even when having defined the same format for all drives in the spectrum protect deviceclass, its handled that way.
Especially in that case, there should be no prioritization based on device type.
Either a drive CAN read/write a tape with the required format, in this case it does not matter if it is a 1155 or a 1160
Or a drive CANNOT read/write the tape, in this case it should not appear in the list of eligible devices at all.

Defining different tape drives into different logical libraries is not feasible, because it massively reduces flexibility of loadbalancing.
It is always better to have a big pool of devices where every drive can be used for everything.

This problem was discussed in cases TS014632092 + TS017482909

Library TS4500
Library-FW 1.11.0.1-C00.00
SpectrumProtect librarymanager: 8.1.20.0