Sourceone and the virtual environment

Hello all,

We installed our Sourceone environment about 2 years ago with EMC's help.  It's running in a VMWare farm with the work drives pointing to raw mapped LUNs, which was required by EMC at the time.  It's working well.  I've tried to add in a new worker and archive server to speed up ingestion of email, but our storage guys are stingy with their LUNs and the new servers only have regular SCSI virtual disks.  Just as I was afraid of, we're not seeing good performance from the new servers.  Are raw LUNs still a requirement for the work drives and if not, what are some suggestions to increase I/O on a virtual disk?

We're running Sourceone 6.7 SP2 and VMWare ESX 4.1.

Thanks,

Bryan