One of my colleagues asking: what's the upgrade pattern of Network Switch if he has 1000 VMs. Here is my answer >
There is no limit on core switch in term of volume of VMs. Switch capacity doesn't depend on VM's quantity, but does on traffic (data transmitted) and number of port on switch to be connected from Compute and Storage.
For example, there are 4 NICs on each Compute and Storage. So each physical node has 16 cores (x3650 in this case), to provision 16 VMs per Compute. Then 1000 VM/ 16 core ~= 60+ physical boxes. This means you need at least 60 Compute nodes. If the ratio of Compute vs Storage is roughly 6:1, you still need another 10 Storage boxes. Finally there are 60+ 10 nodes = 70 boxes (x3650)
70 * 4 NIC/ box = 280 ports.
If 24 ports / switch, => 280/ 24 ~= 12 switches (24 ports/ switch) you'll need. You should also consider the contingency, like 5%.
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Re: How many Network Switches per 1000 VMs?
20120802T22:24:16ZThis is the accepted answer. This is the accepted answer.Interesting...
I assume the VMs are configured with 4 x vCPU with the further assumption that we are achieving a pCPU:vCPU ratio of 1:4.
How would these numbers change if the compute nodes where HS23 blades, keeping the storage nodes as x3650 M4s (probably with local storage)? 
Re: How many Network Switches per 1000 VMs?
20120806T15:58:51ZThis is the accepted answer. This is the accepted answer. PeterTuton
 20120802T22:24:16Z
Interesting...
I assume the VMs are configured with 4 x vCPU with the further assumption that we are achieving a pCPU:vCPU ratio of 1:4.
How would these numbers change if the compute nodes where HS23 blades, keeping the storage nodes as x3650 M4s (probably with local storage)?
+ single pCPU divided into 4 vCPU
+ Each VM has 4 vCPU => 1 VM/pCPU
+ 1000VM = 1000 pCPU = 1000 / (12 core/ blade) ~= 83 blades
+ 83 blade / (14 blade/ blade center, fully equiped) = 6 blade center
+ 6 blade center * 4 NIC/ center (at least) = 24 ports => for Compute
Assume 1:6 = Storage:Compute => at least 4 Storage node
+ 4 x3650 * 4 NIC/ box = 16 ports
Therefore you need 24+ 16 = 40 ports at least :P J