Migrate Backupexec2012 storage

Hello all !
 

I searched for this issue a lot but i couldn't find exactly what i need,

it's pretty simple, we bought a new NAS and we connected it to the backupexec server (via iSCSI) , now we need to migrate all previous backups (B2D) files to the new storage which is also B2D, the backups are around 3.5TB in total size

Any ideas how can we do it ?

Thank you in advance