Disk Storage: space management

Hi,

I have a BE2012 v.14.0 Rev.1798 (64-bit) on windows 2008 server datacenter and 3 disk storage in iSCSI.

I run the jobs backup with 'any disk storage' in option for all backup jobs.

I have the first storage full and the second and third storage not used.

I have the ability to better distribute the load on the storage?

thanks