6.5.1

Table 1‑93. Data Counters
Chart Label Description
virtual_machine Amount of host memory used by the virtual machine for its guest operating system's physical
memory. Memory overhead is not included in consumed memory.
consumed memory = memory granted - memory saved from page sharing
For example, if a virtual machine has 100 MB of memory that is shared equally with three other
virtual machines, its portion of the shared memory is 25 MB (100 MB ÷ 4 VMs). This amount is
counted in the memory consumed data counter.
n
Counter: consumed
n
Stats Type: Absolute
n
Unit: Megabytes (MB)
n
Rollup Type: Average (Minimum/Maximum)
n
Collection Level: 1 (4)
Chart Analysis
A virtual machine's memory size must be slightly larger than the average guest memory usage. This enables
the host to accommodate workload spikes without swapping memory among guests. Increasing the virtual
machine memory size results in more overhead memory usage.
If sucient swap space is available, a high balloon value does not cause performance problems. However, if
the swapin and swapout values for the host are large, the host is probably lacking the amount of memory
required to meet the demand.
If a virtual machine 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 meet the memory requirements. This
leads to memory reclamation, which might degrade performance. If the active memory size is the same as
the granted memory size, demand for memory is greater than the memory resources available. If the active
memory is consistently low, the memory size might be too large.
If the host has enough free memory, check the resource shares, reservation, and limit 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 machine.
If lile free memory is available, or if you notice degradation in performance, consider taking the following
actions.
Table 1‑94. 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, this 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.
vSphere Monitoring and Performance
66 VMware, Inc.