Storage

Dear All,

i have a VM with 3vCPU and 12 GB of RAM running heavy tasks on it.

Customer reports that on every monday the VM goes unavailable for 10 minutes and it affects production.

Earlier VM Settings are below:

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VM - Guest OS-w2k3

RAM-12GB Limit set as 1GB

CPU- Limit set as 1.47ghz

So i Found that May be  the VM Constraint for CPU Resources and Removed the Limit in Resource Allocation and Set as unlimited CPU Cycles to VM.

And this monday Customers reporting the same Issue.So i think the VM is not constraint for CPU Cycles.

So i Thought of removing the Limit on Memory too( thinking to set unlimited), Please advise is this cause any performace problems in VM/DRS Cluster( I have enough Memory in Cluster).

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Below is the idea i captured on VMware Performace Troubleshooting guide, May i Proceed with Memory Setting change as Unlimited.

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Increase the amount of memory allocated to the virtual machine. This action decreases disk and or network activity for applications that cache. This might lower disk I/O and reduce the need for the host to virtualize the hardware. Virtual machines with smaller resource allocations generally accumulate more CPU ready time.

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Thanks and Regards,

Rajesh

You should remove the limit on the RAM as well.

If the OS thinks is has 12GB but the Hypervisor limits it to 1GB the machine will not perform properly.

This KB Impact of virtual machine memory and CPU resource limits (1033115) will provide some more explanation

Hi,

remove the limits. If necessary change the memory size of the VM - but better do not work with limits.

regards

By setting the memory limit when the VM needs more than the 1 GB the vmkernel will utilize the vmkernel swap file which will seriously impact VM performance -