Hi all, I'm just curios and would like some input from the community on this one. We're busy budgeting for a couple of new servers and I thought it would be good to try out the Core i7 CPU's, but see the majority of them don't offer VT-d, but just VT-x. Looking at the LGA1366 range, only the "Intel lga1366 i7 980XE" (from the list of what our suppliers stock) have VT-d, and it costs 4x more than "Intel lga1366 i7 930" or 2x more than "Intel lga1366 i7 960". From a budget perspecitve I could purchase 4 more CPU's, which could translate to 40x - 80x more VM's being hosted for the same capital outlay. Experience has shown that we under-utilize CPU's by a great margin and memory / HDD IO is our biggest bottleneck on any server. 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 Website: http://www.SoftDux.com Technical Blog: http://Blog.SoftDux.com Office: 087 805 9573 Cell: 082 554 7532
> 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 > SoftDuxVT-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 architecturesystems 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 [1] http://wiki.xensource.com/xenwiki/VTdHowTo
Hi,> I'm just curios and would like some input from the community on this > one. We're busy budgeting for a couple of new servers and I thought it > would be good to try out the Core i7 CPU's, but see the majority of > them don't offer VT-d, but just VT-x. Looking at the LGA1366 range, > only the "Intel lga1366 i7 980XE" (from the list of what our suppliers > stock) have VT-d, and it costs 4x more than "Intel lga1366 i7 930" or > 2x more than "Intel lga1366 i7 960".How about the Xeon processors? Are they cheaper than the i7-980XE there? Also keep in mind your board has to support VT-D as well.>From a budget perspecitve I could > purchase 4 more CPU's, which could translate to 40x - 80x more VM's > being hosted for the same capital outlay. Experience has shown that we > under-utilize CPU's by a great margin and memory / HDD IO is our > biggest bottleneck on any server.>From this it seems that you would be running 10 to 20 VM per machine.According to Intel, it's not recommended if the physical NIC is shared. So in your case, the VT-d issue might be moot.
On 09/15/10 2:19 AM, Rudi Ahlers wrote:> Hi all, > > I'm just curios and would like some input from the community on this > one. We're busy budgeting for a couple of new servers and I thought it > would be good to try out the Core i7 CPU's, but see the majority of > them don't offer VT-d, but just VT-x. Looking at the LGA1366 range, > only the "Intel lga1366 i7 980XE" (from the list of what our suppliers > stock) have VT-d, and it costs 4x more than "Intel lga1366 i7 930" or > 2x more than "Intel lga1366 i7 960". From a budget perspecitve I could > purchase 4 more CPU's, which could translate to 40x - 80x more VM's > being hosted for the same capital outlay. Experience has shown that we > under-utilize CPU's by a great margin and memory / HDD IO is our > biggest bottleneck on any server. > > 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. >Core I7 is the branding for the desktop CPU family. The Server processors are branded Xeon 5500 and 5600 (for dual socket servers) and Xeon 7000 for 4+ socket servers. Typically, desktop processors go with desktop motherboards which don't support ECC memory, probably don't have remote management features, likely don't readily support redundant power, and often have only a single NIC onboard. A server board will likely have significantly more IO bandwidth, oriented towards network and disk IO rather than graphics. IMHO, the dual socket 5600 family is the sweet spot of price/performance for a VM host, with 2 x 6 cores, and typically 12 memory slots (2x3 per CPU). populate the memory with 6 matching DIMMs for best performance.
On Thursday, September 16, 2010 03:37:23 am John R Pierce wrote:> On 09/16/10 12:16 AM, Rudi Ahlers wrote: > > Yet the server vendors ship servers, with server chassis, hardware > > RAID, redundant power supplies, etc& offer Core i7 options. How does > > that work? > > low end servers, i guess. I'd have to see a specific model to comment > specifically.Dell's PowerEdge R210 and R310 are available with Core i3.
On Wed, Sep 15, 2010 at 11:19:38AM +0200, Rudi Ahlers wrote:> Hi all, > > I'm just curios and would like some input from the community on this > one. We're busy budgeting for a couple of new servers and I thought it > would be good to try out the Core i7 CPU's, but see the majority of > them don't offer VT-d, but just VT-x. Looking at the LGA1366 range, > only the "Intel lga1366 i7 980XE" (from the list of what our suppliers > stock) have VT-d, and it costs 4x more than "Intel lga1366 i7 930" or > 2x more than "Intel lga1366 i7 960". From a budget perspecitve I could > purchase 4 more CPU's, which could translate to 40x - 80x more VM's > being hosted for the same capital outlay. Experience has shown that we > under-utilize CPU's by a great margin and memory / HDD IO is our > biggest bottleneck on any server. > > 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. >VT-d is marketing term for Intel's IOMMU (IO MMU) implementation, and it's used *only* for PCI passthru, aka giving guest VM direct PCI access to some physical PCI device (nic, hba, etc) on the host hardware. Xen can actually do PCI passthru *without* VT-d for PV guests, but for Xen HVM guests you *need* VT-d (if you want to use PCI passthru). VT-d is NOT required for running HVM/Windows guests. VT-x is the CPU feature that makes it possible to run unmodified guests. VT-d is the chipset IOMMU feature for PCI passthru. See: http://wiki.xensource.com/xenwiki/XenPCIpassthrough -- Pasi