On Wed, Sep 15, 2010 at 1:28 PM, Alexander Dalloz ad+lists@uni-x.org wrote:
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.
ok, that's kinda what I thought as well. We don't use Windows VM's, but rather dedicated Windows servers if needed.
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.
That's what I found as well so I want to concentrate on better I/O throughput. In general we don't saturate the 1GB NIC's. As soon as it gets to a certain threshold, we move some of the VM's to a new server instead. I guess I could look into dual / quad NIC bonding, but that would mean downtime on the server while the NIC's are installed.
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?
Generally we use systems with 8cores+, i.e. Quad Core with HT, or dual Quad Core with HT. But I want to see if I could use the money spend on those expensive CPU setups more wisely with RAM & I/O.
Regards
Alexander
[1] http://wiki.xensource.com/xenwiki/VTdHowTo
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