Which of the following actions should be taken?

Users are complaining that a Windows application server Virtual Machine configured with 1GB RAM is not performing satisfactorily. An administrator opens the Performance Tab for the guest virtual machine and adds the counter for Memory Ballooned in MB. The Performance Chart displays 0 in balloon’s value and a value of 240 in swap usage.

Which of the following actions should be taken?

A.
Adjust the Mem.CtlMaxPercent to read 75.

B.
Install VMware tools

C.
Migrate the Virtual Machine to another host.

D.
Add more memory to the Virtual Machine.

Explanation:
The Performance Chart displays 0 in balloon’s value and a value of 240 in swap usage
the meaning: no balloon but only paging is used = missing VMware tools

Memory Balloon.
This counter reflects the total amount of memory the VMkernel is effectively "borrowing" from virtual machines via the VMTools balloon driver running inside the guest OS. Balloon driver activity indicates over-commitment of ESX host memory. By default, the VMkernel may balloon up to 65% of a virtual machine’s configure RAM. Users are complaining that a Windows application server is not performing satisfactorily. The Memory Balloon counter indicates that memory is being borrowed by the Vmkernel from the virtual machine, indicating that the host has insufficient memory to service requirements from all virtual machines. Therefore either more memory should be added to the host or the guest should be moved to a system with more free memory.

Reference: Memory Provisioning Recommendations for VMware Infrastructure 3 Operational Best Practices, page 11.

8 Comments on “Which of the following actions should be taken?

  1. ServerEngineer says:

    Hi,
    Is the answer of adding of more RAM to VM is correct? To me yes, but why the first para of explanation says “missing tools” .

    To me, VM is swapping out to disk which is clearly more usage in paging and VM needs more memory. Can someone confirm? Thanks.

  2. Jon says:

    Correct answer is B. D is incorrect because the ESX host is swapping the VM memory to disk. Giving more memory to the VM would only make more memory get swapped to disk. The first step to fixing this problem would be installing VMware tools. It will allow the balloon driver to function and let the guest OS choose which memory pages to swap to it’s disk rather than allowing the host to arbitrarily grab random memory pages that may be critical to the VM’s performance. If the host is still so memory constrained that it can’t support the VM’s, the VM should be migrated to another host.

  3. Mohsin Alvi says:

    As per explanation, ANS should be C.
    Why ?
    ESXi uses swapping when no physical memory available on the Host.

  4. Rich says:

    Answer is D. Tricky Question:

    ASSUMING that the poor performance is due to a memory issue (should look at task manager to confirm):

    Ballooning won’t help since it would reduce the physical memory accessible to the VM and cause more swapping, so A & B wouldn’t help.

    There’s nothing in the question that indicates that there is contention on the host, so C wouldn’t help. There’s also nothing indicating that there is not contention. IF VMTools are installed on the VM, then 0 ballooning indicates that there is no contention and C definitely would not help. However, if VMTools are not installed on the VM then ballooning would be 0 even if there is contention.

    I’d ASSUME that VMTools are installed, so there is no contention and D would be the correct answer.


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