6.5.1

If the memory usage value is high, and the host has high ballooning or swapping, check the amount of free
physical memory on the host. A free memory value of 6% or less indicates that the host cannot handle the
demand for memory. It leads to memory reclamation, which might degrade performance.
If the host has enough free memory, check the resource shares, reservation, and limit seings of the virtual
machines and resource pools on the host. Verify that the host seings are adequate and not lower than those
set for the virtual machines.
If the host has lile free memory available, or if you notice a degradation in performance, consider taking
the following actions.
Table 1‑62. Memory Performance Enhancement Advice
# Resolution
1 Verify that VMware Tools is installed on each virtual machine. The balloon driver is installed with VMware Tools
and is critical to performance.
2 Verify that the balloon driver is enabled. The VMkernel regularly reclaims unused virtual machine memory by
ballooning and swapping. Generally, it does not impact virtual machine performance.
3 Reduce the memory space on the virtual machine, and correct the cache size if it is too large. This frees up memory
for other virtual machines.
4 If the memory reservation of the virtual machine is set to a value much higher than its active memory, decrease the
reservation seing so that the VMkernel can reclaim the idle memory for other virtual machines on the host.
5 Migrate one or more virtual machines to a host in a DRS cluster.
6 Add physical memory to the host.
Memory (MBps)
The Memory (MBps) chart displays the swap in and swap out rates for a host.
This chart is located on the Home view of the Host Performance tab.
Table 1‑63. Data Counters
Chart Label Description
swapinRate Average rate at which memory is swapped in from the host swap le.
n
Counter: swapinRate
n
Stats Type: Rate
n
Unit: MegaBytes per second (MBps)
n
Rollup Type: Average (Minimum/Maximum)
n
Collection Level: 1 (4)
swapoutRate Average rate at which memory is swapped out to the host swap le.
n
Counter: swapoutRate
n
Stats Type: Rate
n
Unit: MegaBytes per second (MBps)
n
Rollup Type: Average (Minimum/Maximum)
n
Collection Level: 1 (4)
Chart Analysis
Host memory must be large enough to accommodate virtual machine workload. Transient high-usage
values usually do not cause performance degradation. For example, memory usage can be high when
several virtual machines are started at the same time or when there is a spike in virtual machine workload.
Chapter 1 Monitoring Inventory Objects with Performance Charts
VMware, Inc. 47