[CentOS] Backup Suggestion on C7

Hi list,
I'm building a backup server for 3 hosts (1 workstation, 2 server). I 
will use bacula to perform backups. The backup is performed on disks (2 
x 3TB on mdraid mirror) and for each hosts I've created a logical volume 
with related size.

This 3 hosts have different data size with different disk change rate. 
Each host must have a limited sized resource and a reserved space. If a 
server needs more space to perform backup, It must be enabled and 
provisioned.

My first solution was put each host pools on different logical volumes, 
like:

host1 -> lv1
host2 -> lv2
host3 -> lv3

and store pools/volumes on specified storage daemon that uses a 
specified device for each different hosts.

host1 -> storage1 -> device_lv1
host2 -> storage2 -> device_lv2
host3 -> storage3 -> device_lv3


  Unfortunately, I can't define on bacula-sd.conf multiple storage 
definition but only multiple devices. To use different storage I must 
run 3 bacula-sd on same host (I can?), run a bacula-sd on a vm/host.
Ah, I must use only one physical server.

With one single machine and the current state I can't use multiple 
storage daemons.

There are other ways to store host volumes on different devices?

My second solution was, use only one storage daemon (on the same host) 
with a single device LVM over mdraid, create pool for each hosts and 
limit the size for each volumes on related pool.

Suggestions?

Thanks in advance.