I recently had a customer that had some problems with a HP 1/8 G2 Autoloader LTO 5 Drive.
We discovered some hardware problems and got the LTO 5 Drive replaced under warranty but they also began to run into some more problems with tape backup failures.
I had a support case with Microsoft and discovered a few things to help people in the future if they run into similar problems.
The easiest thing to do is to upgrade DPM2007 to 2010 which 9 times out of 10 will fix the problem and DPM 2012 will be with us soon! However its still always nice to fix tape problems when they occur and listed below are a few ways to help.
1.Open up the DPM Database which is normally servername\MS$DPM2007$
Then browse to a table tbl_MM_Drive and right click on it and click open then ensure that all items in the OperationOccuring field are set to 0 and the click save all.
2.Add a dword value "RSMCompatMode" in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Data Protection Manager\Agent with a decimal value of 27. As per Microsoft KB978901
All tape inventories were failing for me prior to adding this DWORD to the registry.
3.Run DPMLibraryTest.exe to validate mounting and moving of tapes.
4. Run dpmbackup -db to create a backup of your DPM DB which you will need to do if you are upgrading to 2010.
5. One of the weaknesses of DPM is the inability to back up Oracle DB's and Vmware. i365 have a plugin for DPM which can backup oracle & vmware. Yipee! You can read up on it HERE
6. Finally , Erasing tapes in DPM can sometimes take forever , so it would be nice to speed up that process and heres hows.
If your tape drive supports short erase, you can enable it on the DPM server by creating the DWORD UseShortErase under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Data Protection Manager\Agent.
Set the value of the DWORD to 00000000.
After this value is set, all erase operations on the DPM server will be short erases. To revert to long erases, remove this registry key