Writing the old EV VaultStore data before purging into LTO tapes

Hi People,

Can anyone please let me know what is the best possible way to migrate the EV Vault Store into the tapes before I enable the data purging policy for any data older than 5 years ? 

I need to know what are my options to relieve the storage array LUNs across 15 Vault Store Partitions and 3 index partitions.

Any suggestion to free up the disk space in the EV Vault Store that can be retrieved later in the case of litigation would be considered as well.

Thanks in advance.