Slow storage performance when using Fixed Path Policy with multiple VMKernel Ports and Equallogic Storage

Products

• VMware vSphere ESXi

Issue/Introduction

This article explains how to improve slow SAN performance when using Fixed Path pathing policy on Dell EqualLogic iSCSI storage arrays with multiple VMKernel Ports.

Environment

VMware ESX 4.0.x
VMware ESXi 4.0.x Embedded
VMware vSphere ESXi 5.5
VMware vSphere ESXi 5.0
VMware ESX 4.1.x
VMware ESXi 4.1.x Installable
VMware ESXi 4.1.x Embedded
VMware ESXi 4.0.x Installable
VMware vSphere ESXi 5.1

Resolution

The Default pathing policy for Dell EqualLogic Storage Arrays is Fixed Path; this pathing policy is only valid when using a single VMkernel Port. If you are using multiple VMkernel Ports, then Dell EqualLogic recommends using their Multipathing Extension Module (MEM) or Round Robin (RR) as the pathing policy for ESX 4.x.

Note:

• The EqualLogic MEM requires ESX/ESXi 4.1 and/or ESXi 5.0 with Enterprise licensing and array firmware 4.3.7 or higher.
• MEM 1.2 is only compatible with vSphere 5.x and certified on EqualLogic firmware version 5.2. For prior versions of vSphere or firmware use MEM 1.1.x.
  

Using fixed path in a scenario where MEM or RR should be used results in a significant decrease in storage performance.

For more information about the recommended configuration for Dell EqualLogic storage arrays, see:

• Configuring and Installing the EqualLogic Multipathing Extension Module for VMware vSphere and PS Series SANs
• Best Practices when implementing VMware vSphere in a Dell EqualLogic PS Series SAN Environment
  
  Note: The preceding links were correct as of June 13, 2014. If you find a link is broken, provide feedback and a VMware employee will update the link.