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• 2 replies
• Latest Post - ‏2012-08-06T15:58:51Z by j3ffyang
j3ffyang
16 Posts

# Pinned topic How many Network Switches per 1000 VMs?

‏2012-08-02T16:20:28Z |
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%.
Updated on 2012-08-06T15:58:51Z at 2012-08-06T15:58:51Z by j3ffyang
• PeterTuton
14 Posts

#### Re: How many Network Switches per 1000 VMs?

‏2012-08-02T22:24:16Z
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)?
• j3ffyang
16 Posts

#### Re: How many Network Switches per 1000 VMs?

‏2012-08-06T15:58:51Z
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)?
@Peter - my assumption like this (I'm not very sure how many cores on blade HS23, I assume 12 cores = 2* 6). Like what you said, pCPU:vCPU = 1:4 means

+ single pCPU divided into 4 vCPU
+ Each VM has 4 vCPU => 1 VM/pCPU
+ 1000VM = 1000 pCPU = 1000 / (12 core/ blade) ~= 83 blades