How many vCPUs I can assign to UT5.3 in VMware ESX 3.x Virtual Center

[lovelonely]

Hi

Any one knows how many vCPUs that i can assign to UT5.3 in VMware ESX 3.X Virtual Center?

I have successful migrate the UT5.3 from physical box to virtual center {The purpose for migration is we can have a backup UT box if the physical box dead.}. But i had some issues here, please advice.

conditions:
Average 15 emails/min hits the untangle530 EXT interface.

status:
1. UT5.3 with 2 vCPUs, 3G RAM running good.
CPU Usage in MHz(Average/Rate) 1801Mhz~4262Mhz Average:2355.3

2. UT5.3 with 4 vCPUs, 4G RAM running good on 12 hrs then freeze until reset the Vitual Client(Untangle 530)

The Problem is how many vCPUs I can assign to UT5.3 linux system

[TommyBoy]

Assigning more vCPUs can actually degrade VM performance in ESX. All vCPUs in a VM are scheduled at the same time (whether they're handling a thread or not), and each will consume a separate core of the ESX server. If there aren't enough open cores (i.e. they're servicing single-core VMs), then the VM gets rescheduled. In a simple example, if you have an ESX server with only a single Dual-Core CPU, you cannot run a 4-vCPU VM on it since it can never get four cores free at one time. Single vCPU VMs do very well. It's very possible to do a P2V on a 2-CPU machine, knock the VM down to a single vCPU, and increase performance. Of course, your mileage may vary.