I'm planning to run ZFS on Linux (latest Ubuntu stable ppa). The hardware is a xeon E3-1270 with 24 GB of RAM, 6 SAS ports on the motherboard, and a supermicro HBA with 8 SAS ports. I plan to have 4 x 3TB on 5400rpm SATA drives and 4 x 2TB on 7200rpm SATA drives in RAIDZ1 for a start. This will run 2 file servers in virtual machines. The file servers have different performance needs, so one will use the storage from the 5400rpm drives, and the other will use the 7200 rpm drives. The OS will run on a separate SSD.
The question is: how should I configure this (for performance, reliability, etc)?
a. Should I run ZFS on the VM host, and export the logical drive to the VM guest? Or should I export the raw disks to the VM guest and run ZFS on the guest?
b. For the file server with higher performance requirements, should I attach the 4 x 7200rpm drives to the HBA and attach the entire HBA to the VM guest?