6.5.1

Solutions for Memory Performance Problems
Host machine memory is the hardware backing for guest virtual memory and guest physical memory. Host
machine memory must be at least slightly larger than the combined active memory of the virtual machines
on the host. A virtual machine's memory size must be slightly larger than the average guest memory usage.
Increasing the virtual machine memory size results in more overhead memory usage.
Problem
n
Memory usage is constantly high (94% or greater) or constantly low (24% or less).
n
Free memory consistently is 6% or less and swapping frequently occurs.
Cause
n
The host probably is lacking the memory required to meet the demand. The active memory size is the
same as the granted memory size, which results in memory resources that are not sucient for the
workload. Granted memory is too much if the active memory is constantly low.
n
Host machine memory resources are not enough to meet the demand, which leads to memory
reclamation and degraded performance.
n
The active memory size is the same as the granted memory size, which results in memory resources that
are not sucient for the workload.
Solution
n
Verify that VMware Tools is installed on each virtual machine. The balloon driver is installed with
VMware Tools and is critical to performance.
n
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.
n
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.
n
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.
n
Migrate one or more virtual machines to a host in a DRS cluster.
n
Add physical memory to the host.
Solutions for Storage Performance Problems
Datastores represent storage locations for virtual machine les. A storage location can be a VMFS volume, a
directory on Network Aached Storage, or a local le system path. Datastores are platform-independent
and host-independent.
Problem
n
Snapshot les are consuming a lot of datastore space.
n
The datastore is at full capacity when the used space is equal to the capacity. Allocated space can be
larger than datastore capacity, for example, when you have snapshots and thin-provisioned disks.
Solution
n
Consider consolidating snapshots to the virtual disk when they are no longer needed. Consolidating the
snapshots deletes the redo log les and removes the snapshots from the vSphere Web Client user
interface.
Chapter 1 Monitoring Inventory Objects with Performance Charts
VMware, Inc. 95