Installation guide

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VMware ESX Server Administration Guide
Improving Performance
Before deploying all your virtual machines, we suggest that you create a list of all the
virtual machines you plan to run on ESX Server. For each virtual machine, identify its
primary functions and applications. Based on its primary function, determine its
limiting resources. For example, a Web server’s most limiting resource may be
memory, while a terminal services server’s most limiting resource may be CPU.
Similarly, a database server’s most limiting resource may be disk bandwidth.
In this section, we provide some general guidelines on improving performance on
‘VMware ESX Server. However, some of these guidelines may not be appropriate for
you, depending on your particular workplace situation.
Note: Determine which virtual machines are more important and which ones will
benefit more from additional resources. You should not need to optimize each
resource for each virtual machine.
For example, you may want to give more memory shares and a higher memory
minimum to a virtual machine Web server for Platinum customers, compared to a
virtual machine Web server for Silver customers or for an internal Web server.
Note: If you run several virtual machines with similar guest operating systems on ESX
Server, then likely, you will be able to have a higher overcommitment of memory,
without noticing a performance degradation in ESX Server. In general, similar guest
operating systems enable greater memory sharing in virtual machines. See Sharing
Memory Across Virtual Machines on page 408.
Improving Slow Performance
If performance seems slow, first determine whether this slow performance applies to
all virtual machines on an ESX Server, or to just one virtual machine.
Improving Slow Performance on ESX Server
If you notice slow performance on all your virtual machines, then examine CPU usage.
Check and see how much idle time each processor has. Also, check overall system
CPU utilization through the VMware Management Interface. If the processors are not
taxed, and total system CPU utilization is under 80%, then the problem is probably not
CPU usage.
If CPU resources are not the problem, then check if the VMkernel is swapping out
memory. Check the output of /proc/vmware/sched/mem from the procfs
interface in the service console. For more information, see Service Console
Commands on page 412.