Before decommissioning existing setup you should install BE2012 on the new server.
On the new setup make sure the library is detected by Windows and Backup Exec.
Install Micorsoft drivers for the autoloader and Symantec drivers for the tape drive.
Uninstall BE12 remote agent and install BE2012 remote agent on all the remote servers.
Configure new backup jobs and verify if everything is working fine in the new setup.
LTO5 tape drive can read LTO3 tapes but cannot write to it. So load LTO3 tape in the library and
perform an inventory. To perform restore you will need catalogs so you may either copy catalogs
from the older setup or you may run a catalog job on the LTO3 tapes.
Refer to below links before carrying out above steps
For BE2012 Hardware & Software compatibility list and Admin Guide refer to the below link
https://www-secure.symantec.com/connect/forums/adminguides-scls-hcls-backup-exec-all-versions
For Tape Drive and Cartridge Compatibility Matrix refer to the below link
http://knowledgebase.tolisgroup.com/?View=entry&EntryID=178%20(LTO%20compatibility)
Refer to PKH's article on installing BE2012
https://www-secure.symantec.com/connect/articles/preparing-install-or-upgrade-be-2012
Note:
Since you are switching from BE12 to BE2012 I would reccommend you to install BE2012 in a test
environment and get a feel of the new UI and enhanced administration. From the administration point
of view there are lot of new things in the latest version of BE.
