So, if VT-d really necessary? We mainly host XEN virtual machine for the hosting industry, i.e. we don't need / use graphics rendering inside VM's, or need DAS on the VM's, etc.
Kind Regards Rudi Ahlers SoftDux
VT-d is not a necessity in general. It all depends on the kind of virtualization you run. If you run only paravirtualized guests on Xen, then there is not any need for VT-d (see [1]). If you fully virtualize for instance Windows guests, then specific systems may profit i.e. from a reserved network card by better network I/O.
Whether VT-d is useful to have may too depend on whether pricing for the customer can be adjusted when providing such an extra feature.
From own experience I concur that often with most modern x86 architecture
systems the I/O (network and storage) is the bottleneck in the area of virtualization.
Just curious, do you really run virtualization for hosting on systems with uni-processor design? I mean not choosing professional dual quad- or hexa-core processor systems with Nehalem / Westmere Xeon CPUs or their AMD Opteron counterpart?
Regards
Alexander