User guide

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

• Standby – The path to the Vdisk is inactive and must be activated before I/Os can be issued

• Unavailable – The path to the Vdisk is unavailable through this controller

• Transitioning – The Vdisk is transitioning between any two of the access types defined above

The following load-balancing I/O path policies are supported by vSphere 4.x and 5.x:

• Round Robin – ALUA-aware

• Most Recently Used (MRU) – ALUA-aware

• Fixed_AP – ALUA-aware (Introduced in ESX 4.1. Rolled into Fixed I/O in ESXi 5.x.)

• Fixed I/O – Not ALUA-aware

Because they are ALUA-aware, Round Robin and MRU I/O path policies first attempt to schedule I/O requests to a Vdisk

through a path that includes the managing controller.

For more information, refer to Configuring multi-pathing.

Vdisk follow-over

Another important concept that must be understood is Vdisk follow-over, which is closely associated with ALUA.

As described above, ALUA defines which controller in an asymmetric active-active array is the managing controller for a

Vdisk. In addition, follow-over ensures that, when the optimal path to the Vdisk changes, all hosts accessing the Vdisk

change their access paths to the Vdisk accordingly.

Follow-over capability is critical in a vSphere 4.x and 5.x cluster, ensuring that Vdisk thrashing

between controllers cannot

occur. With follow-over, all vSphere servers

accessing a particular Vdisk update their optimal Vdisk access paths

accordingly when the Vdisk is implicitly moved from one controller to the other.

Configuring EVA arrays

HP provides tools to help you configure and maintain EVA arrays. For example, intuitive Command View EVA can be used to

simplify day-to-day storage administration, allowing you to create or delete Vdisks, create data replication groups, monitor

the health of system components, and much more. For batch operations, HP recommends using Storage System Scripting

Utility (SSSU), a command-line tool that can help you quickly deploy large EVA configurations, back them up for future

deployments, and perform advanced administrative tasks.

When configuring a large number of Vdisks for a vSphere 4.x and 5.x implementation, such as that described in this paper,

you should configure the Vdisks to alternate between EVA controllers using either Path A-Failover/failback or Path B-

Failover/failback (see Vdisk provisioning).

Appendix A: Using SSSU to configure the EVA presents a sample script that creates multiple Vdisks, alternates path

preferences between two controllers, and presents the Vdisks to vSphere servers.

This section outlines the following options for configuring an EVA array:

• Using Command View EVA

• Running Command View EVA within a VM

• Using the HP Insight Control Storage Module for vCenter

Backward and forward transitioning

Also known as ESX servers