Locating VMware Memory Issues in Host and Virtual Machines.

Host and Virtual Machines memory

Find out how much RAM is available on the host ESX server:

  1. ESX host > Configuration Tab > Memory
  2. Summary Tab > Resources > under capacity.

Find out how much RAM is available on the guest machine

  1. Under general  > memory
  2. Memory overhead is the usage of the host kernel for the specified guest.
  3. Consumed host memory: how much RAM the guest is actually using.
  4. Virtual machines tab > look at how much RAM each guest is consuming.

Important memory metrics in vmware. Can be found on vm or host.

  1. Average memory consumed (Mem.active.averge) = memory granted-memory saved ny sharing, is the amount of memory consumed by all VMs.

a)      Average memory active– amount of memory that is estimated to be used based on recently touched memory pages.

b)      Memory consumes – actual memory that the vm pinned out of the total capacity.

c)       Memory granted – the sum of all the memory granted to virtual machined guests. Can be higher then your physical RAM.

  1. Average memory swapped in/out (mem.swapin.average) – virtual memory swapped to or from the disks. Can indicate that the host is suffering of memory contention.
  2. Average memory swapped (mem.swapped.average) total amount of memory swapped out. Can indicate that the host is suffering of memory contention.
  3. Average memory reclaimed by ballooning (mem.vmmemctl.average) – memory reclaimed by using ballooning. Can indicate that the host is low on RAM, over provisioning and memory contention.

Measurements to take under performance tab: Swap used, Swap out, Swap in, Consumed, Active, Usage, Balloon, Granted, Shared common, Consumed.

When is host memory a problem?

  • Consumed memory is approaching total host memory.
  • Active memory approached total memory
  • Ballooning occurs
  • Host swapping is occurring

When is guest memory a problem?

  • Guest VM memory has high % utilization in vsphere client.
  • View memory stats inside the guest.

 

Use esxtop to locate problems.

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