Placing Backup Repositories

We have some Windows and Linux VMs used as repositories for backup products like Veeam.  These tend to require very large virtual disks >3TB, greater than our normal LUN size on ESXi clusters (2TB).  We want to keep our LUN sizes consistent on ESXi clusters.

Should the storage for my backuip repositories' VMDKs be on the ESXi clusters themselves, should it be elsewhere such as a data domain device?

Thanks!