c7000 with 6G SAS switches, D6000 disk enclosure - Mulit-initiator mode.

[Mike_ADL]

Hi All,
I have a c7000 enclosure with 14 x BL460c blade servers and a severe lack of attached SAN space.  The enclosure is configured as follows:

• All  servers have a pair of local 300 Gb RAID 1 drives.
• Some servers only use the local RAID 1 storage.
• Many of the blade servers are VMware ESXi 5.1 hosts with a FlexFabric 10Gb 2-port 554M adapter (mezzanine slot 1)connected to 3PAR SAN storage.  (Two VMware farms.)
• Several other blade servers are Windows 2008 R2 with MS Exchange 2010 hosts with a Smart Array P721m adapter, connected to a D6000 storage array.
• About half the 2 TB drives in the D6000 are not used.

The problem we have is that the 3PAR SAN is at capacity and it can't be expanded as the 256 GB drives can no longer be purchased, so we can not populate the last available 16 drive bays.
A possible solution would be to install a P721m into mezzanine 2 of each of the 4 hosts in one of the VMware farms and use available disks from the D6000 instead of the 3PAR SAN.  This would free up about 6½ TB of SAN storage.

My questions are:

1. Am I correct in thinking that the 6G SAS Blade Switch, Advanced Option, "Multi-initiator Mode" needs to be enabled?
2. When the Multi-iniator Mode is enabled, what effect will it have on the blade servers that have an existing zone assigned to them?
3. Is there any problem in temporarily having an ESX host with a connection to the 3PAR SAN and the D6000 disk enclosure simultaneously?
4. What else needs to be considered?

Cheers,
Mike.