Cpu virtualization conversion

Hello ,

I have about 17 physical servers I wish to provide the cpu processing power needed to virtualize. They were a mismatch of different hp generations , i took the average cpu of  each one and multiplied by the sum of the processing sockets clock speed ( example 15% usage multiplied by 2 sockets at 2400   (.15 * 4800 = 720 Mhz ) ) . I then did this for all 17 servers and came up with a sum of 18206 Mhz .

The server I wish to virtualize with is a dellR920 , 2 x E7-4809 V2 1.9Ghz 6 Core Processors (Option for 2 more)   . So am I good ? Do I multiply 1900 * 6 ( cores) * 2 =  22800 . I know I should leave 20% for the host processing , but is my calculations correct? . This will be with vmware 5.5
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Yes, as a theoretical  calculation, that should be fine.

Memory is often the bottleneck not cpu.
Nathan HawkinsTechnical Lead - Network SecurityCommented:
Thats cutting it awfully close. You have used an average utilization of 15% which means all that has to happen is some of those servers spike to 30% (let alone 90%) and yer whole system begins to crash...

17 servers on a max of 8 cores isnt wise. Im not sure Id even leverage at a 2:1 ratio let alone 3-4:1 meaning yer at 6 cores now and you want to leverage 17 servers on those 6 core and each server will probably get minimum dual core but lets face it apps like resources so some could be quad core setups which translates the ratio beyond 4:1 ratio... The most VMs Id put on the 8 core host is 8 (maybe 10)... 17 and its going to crawl... For 17 servers you are going to want 20 available CPU cores or more.

As previously mentioned tho you are going to run into worse bottle necks. The biggest I find is networking. How many NICs do you have on the box? 1 or 2 at 1 Gb/s speed? serving the box itself and 17 VMs? When bonded thats still grossly inadequate and will also make any connections to that box and its VMs crawl... I run dual 10Gb nics bonded to my my box of 15 VMs and its still not real speedy...

Now 8 servers on a dual 1Gb/s bonded interface wouldnt be horrible... but still not great...

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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
and what happens, when all your eggs are in one basket, and the host is not available, all 17 servers are also down!

So maybe you need two hosts!
davesnbAuthor Commented:
Yes  I agree, I  plan on running 4 x E7-4809 V2 1.9Ghz 6 Core Processors . Thanks for the info on the networking will look into..
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