Information Technology Reference
In-Depth Information
These counters, in particular the Memory Swap Used (Average) counter, will give you an idea
of whether the ESXi host is under memory pressure. If the ESXi host is not suffering from mem-
ory pressure and you still suspect a memory problem, then the issue likely lies with the VM.
Perform the following steps to create a real-time chart for a VM's memory usage:
1.
Use the vSphere Web Client to connect to a vCenter Server instance.
2.
Navigate to either the Hosts And Clusters or the VMs And Templates view.
3.
In the Navigator, click a virtual machine. This shows you the Summary tab.
4.
Click the Performance tab, and switch to the Advanced view.
5.
Click the Chart Options link.
6.
In the Chart Options dialog box, select the Memory resource type and the Real-Time dis-
play interval.
7.
Select Line Graph as the chart type.
8.
In the list of counters, select to show the Memory Usage (Average), Memory Overhead
(Average), Memory Consumed (Average), and Memory Granted (Average) counters. This
shows memory usage, including usage relative to the amount of memory coni gured for
the VM.
9.
Click OK to apply the chart options and return to the Performance tab.
From this performance chart, you will be able to tell how much of the memory coni gured for
the VM is actually being used. This might reveal to you that the applications running inside that
VM need more memory than the VM has been assigned and that adding more memory to the
VM—assuming that there is sufi cient memory at the host level—might improve performance.
Memory, like CPU, is just one of several different factors that can impact VM performance.
Network usage is another area that can impact performance, especially perceived performance.
Monitoring Network Usage
vCenter Server's charts provide a wonderful tool for measuring the network usage of a VM or
a host.
Monitoring network usage requires a slightly different approach than monitoring CPU or
memory. With either CPU or memory, reservations, limits, and shares can dictate how much of
these two resources can be consumed by any one VM. Network usage cannot be constrained
by these mechanisms. Because VMs plug into a VM port group, which is part of a vSwitch on a
single host, how the VM interacts with the vSwitch can be manipulated by the virtual switch's
or port group's policy. For instance, if you need to restrict a VM's overall network output, you
would coni gure trafi c shaping on the port group to restrict the VM to a specii c amount of
outbound bandwidth. Unless you are using vSphere Distributed Switches or the Nexus 1000V
third-party distributed virtual switch, there is no way to restrict VM inbound bandwidth on
ESXi hosts.
