“Tape Persistence” means that the tape drives for a tape library use symbolic names. These names stay unique during server reboots, no matter in which order the operating system discovers the tape drives. Without the feature during reboots it could be possible that the SCSI addresses are changed.
Normally the default behaviour of Windows is not a problem for Data Protector since the mechanism “Automatically detect changed SCSI addresses” will discover the new SCSI addresses using the serial number of the tape drive. However, in environments with several tape libraries attached to a server (i.e. when virtual tape libraries are used) the default Windows behaviour might mix the SCSI addresses between different library tape drives. The integrated mechanism in Data Protector will require in these cases some time to correct the problem with the changed SCSI addresses and will display some errors during the jobs. Using tape persistence the behaviour of Windows will be changed and in example a tape drive named “Tape0” becomes a symbolic name “Tape1236572535” (the symbolic name cannot be configured). With these new names error messages in Data Protector are prevented and the SCSI addresses or tape names stay unique.
To enable tape persistence for Windows copy the code below, insert into text editor and save the content as .reg file. Execute the reg file and reboot the System. In addition RSM is disabled. Don’t forget to install the HP tape drivers, the installation routine can be downloaded within the corresponding HP Library.
Update: To use persistence fot the library robotic the additional key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MChgr\Persistence=00000001 is required. In this example the device Changer1:0:0:0 becomes the symbolic name Changer2147483646:0:0:0. With this feature enabled the robotic stays unique as it is the case with tape drives during reboots.
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\hplto] "AutoRun"=dword:00000000 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Tape] "Persistence"=dword:00000001 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MChgr] "Persistence"=dword:00000001 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NtmsSvc] "Start"=dword:00000004