VMWare Troubleshooting BasicsLewis Talley

Memory

• ESXi incorporates a number of memory management techniques such as (transparent page sharing, Ballooning, Host Swapping, and Compression) to better manage memory

• Ballooning: ESXi can use ballooning to force a VM to give up memory pages that the guest OS considers least valuable. This causes the VM to “inflate” its local balloon (page file)• Will respond as fast the

datastore the swap is on, but slower than RAM.

What to look for

CPU

CPU Ready – the percentage of time a vCPU is ready to execute, but it waiting for the hypervisor to schedule it to execute.VMWare recommends keeping this below 5%. This means that we need to right size our guests

CPU Ready – an example

• Noticed sluggish guest performance

• Reduced vCPU count from 4 to 2

• Guest performance increased and CPU Ready decreased

Disk

• Understanding where disk latency can come from

• Metrics are available (below) and can be analyzed graphically by tools such as esxplot (free)

• Report card InSource developed..

Network

• Percentage of dropped packets (should be less than 1)

• Can be caused by variety of reasons• Sometimes hard to see with vSphere

client (since data is aggregated)

ESXTop Network Issues

• Here we can see a VM that is dropping 6% of packets

Helpful utilities

• ESXPlot• Allows you to graphically

visualize ESXTop output• VisualESXTop

• Similar to ESXPlot• IOMeter

• Used to test performance of storage

• Wireshark• Helpful in analyzing network

traffic

Questions? Contact us..

Ltalley@insourcess.com

Thank You!