Problem:

Data Protection Manager (DPM) does not work with new Ultrium-5 LTO-5 tape drive. DPM Library only provides options to clean drive or disable drive. DPM does not correctly identify and detect the new tape drive.
Hardware: HP StoreEver LTO-5 Ultrium-5 tape drive. N.B., this solution works with just about any LTO drive.

 Background: 

 Old LTO-3 drive was running out of space. Purchased HP LTO-5 drive to expand available storage from 800GB to 1.5TB:

• Server has compatible SAS HBA and cable.
• Device Manager recognizes the new drive after a simple hardware swap.
• DPM lists the new hardware under its Libraries.
• Protection groups changed and reflect new hardware. 

 Solution:

 Update the DPMLA.xml file to reflect the new hardware:
C:\Program Files\Microsoft DPM\DPM\Config\DPMLA.xml
XML Before:

<drivelibraryassociation>
<drive drivebayindex="0" scsibus="0" scsilun="0" scsiport="2" scsitargetid="5" serialnumber="HUExxxxxxx">
<library scsibus="-1" scsilun="-1" scsiport="-1" scsitargetid="-1" serialnumber="">
</library></drive></drivelibraryassociation>

XML After:

<drivelibraryassociation>
<drive drivebayindex="0" scsibus="0" scsilun="0" scsiport="2" scsitargetid="5" serialnumber="HUExxxxxxx">
<library scsibus="-1" scsilun="-1" scsiport="-1" scsitargetid="-1" serialnumber="">
</library></drive></drivelibraryassociation>

Tips:

• Serial is located on the physical tape drive. 
• Use the HPE Library and Tape Tool to identify SCSI assignments. 
• Alternately, identify SCSI assignments in the Device Manager → Tape drive → Properties →Details → Location information property.

Final Steps:

• Save changes to DPMLA.xml and restart DPM services. 
•  Rescan the DPM tape library. 
• Inventory tape library.

That's It!

References:

DPM Network Administration