transfer type in VMWARE backups.

Hi

Master Win 2012, 7.6.0.1
Media WIN 2012, 7.6.0.1
STU : MSDP
Backup : FUll type
client virtual machine RHEL6.
Backup host : Media server  it self which is virtual media server.
policy VMWARE, quiescing enabled.

When we are initiating backups with transfer type SAN, hotadd, backups are failing with following msg.
"Error bpbrm (pid=3788) from client Server04:ERR - Error opening the snapshot disks using given transport mode: Status 23"

When we are initiating it with NBD transfer type, it works, but with very low speed.

how to make it working on SAN & hotadd transfer type.
how speedof backup can be increased.