User guide

Technical white paper | HP Enterprise Virtual Array Storage and VMware vSphere 4.x and 5.x configuration best practices

Table 14 shows the differences between UNMAP operation in ESXi 5.0 and ESXi 5.0U1 and later.

Table 14. Differences in UNMAP operation in ESXI 5 versions

ESXi 5.0

ESXi 5.0U1 and later

Single automated operation

Manual Step 1

VM/VMDK is deleted

Used blocks are freed in VMFS

ESX sends UNMAP requests to storage

Manual Step 2

Storage frees physical blocks

Space reclamation utility invoked

VMFS creates a temp file for capacity allocation

ESX sends UNMAP to the temp file block range

Storage frees physical blocks

Summary of best practices

How can I best configure my storage?

• To size an EVA disk group, start by understanding the characteristics of the application’s workload to ensure the

virtualized environment is capable of delivering sufficient performance.

• Using a single EVA disk group is typically sufficient to satisfy all your storage optimization objectives (cost, performance,

and capacity).

• Fill the EVA with as many disks as possible, using the largest, equal-capacity disks.

• The single-drive protection level should be sufficient for your disk group unless MTTR is longer than seven days.

• Do not use Vraid6 unless absolutely necessary. Vraid5 is less expensive and provides adequate redundancy for a vSphere

deployment.

• When using disks with differing performance characteristics, use a single disk group rather than multiple disk groups each

containing disks of the same characteristics.

• Alternate controller ownership for EVA Vdisks between Controller A and Controller B using the Path-A-Failover/Failback

or Path-B-Failover/Failback setting.

• Ensure that the managing controllers for DR groups are spread between Controller A and Controller B to maintain an

adequate balance in the system configuration.

• The VMware host mode must be used on the EVA for proper operation of the UNMAP primitive with ESX.

• UNMAP is not supported by VMs accessing RDM volumes presented to ESX hosts. Use, VMDirectPathIO or NPIV and give

exclusive access of the volume to the VM with appropriate host mode.

• VMFS datastore must be aligned to either 64KiB or 1MB boundary for use with HP EVA Storage UNMAP integration.

Which is the best I/O path policy to use for my storage?

• Round robin I/O path policy is the recommended setting for EVA active-active arrays except for Vdisks used by an MSCS

cluster, which should be set to MRU.

MRU is also suitable for other applications if round robin is undesirable in a specific environment.

• Avoid using Fixed I/O path policy with vSphere 4.x/5.x and an EVA array.

• Configure round robin advanced parameters to IOPS=1 for vSphere 4.x/5.x.

• For normal production I/O, avoid using Fixed_AP I/O path policy with vSphere 4.1 or its equivalent Fixed I/O path policy

with vSphere 5.x and an EVA array.

However, you can leverage Fixed_AP I/O path policy (vSphere 4.1) and Fixed I/O path policy (vSphere 5.x) to quickly

rebalance the Vdisk configuration after a controller has been restored from failure. Use just one vSphere 4.1/5x server

from the cluster; ensure the array is not under heavy load.