Release Notes

Host based connectivity and high availability
3 Best Practices for Implementing VMware vSphere in a Dell PS Series Storage Environment | TR1091 | v1.3
2 Host based connectivity and high availability
Several best practices should be implemented when connecting VMware vSphere/ESXi servers to PS Series
storage to ensure optimum performance and high availability.
2.1 Keep ESXi updated to current revision
It is important to ensure that the most current ESXi version, also known as the build number, is installed.
Using the VMware vSphere Web client, select an individual ESXi server under Hosts and Clusters, and
expand the Configuration window to display the version and build number. When using the VMware vSphere
Web client, select an individual ESXi sever to display the version and build number. VMware Update
Manager, part of vSphere vCenter, provides this updating functionality.
2.2 iSCSI subnets and routing recommendations
iSCSI port binding is required for Round Robin and EqualLogic Multipath Extension Module (MEM) MPIO with
PS Series storage. Versions of VMware vSphere prior to 6.5 do not support routing when using the iSCSI port
binding (described in the VMware KB article 2038869). As a result, the VMkernel ports used to communicate
with the PS Series storage must be on the same subnet and able to communicate directly with the SAN and
not through a gateway with vSphere versions older than 6.5. Although routing of iSCSI with the use of port
binding is supported using vSphere version 6.5 or newer, routed iSCSI environments should only be used
when accessing replicas at a remote site for faster verification or restoration of a single virtual machine.
2.3 Jumbo frames
Jumbo frames are not required but are recommended for improved iSCSI performance. In order to support
jumbo frames the vmnic, ESXi VMkernel ports, and vSwitch must be configured to use an MTU of 9000. The
physical switches must also be capable of using jumbo frames and properly configured for them.
When using iSCSI offload cards, verify the compatibility of the cards and support for jumbo frames before
enabling it in the environment.
2.4 CHAP authentication for access control
Manipulating MPIO modules and increasing volume sizes are both great ways to manage volume iSCSI
connections. There are other best practices and recommendations that can help control how connections are
made to PS Series volumes. CHAP authentication for access control lists is the preferred method of volume
access authentication from an ease of administration point of view.
Each PS Series volume ACL (access control list) has a maximum of 16 entries (unrelated to iSCSI
connections) that can be CHAP accounts, IQN strings or IP addresses. In keeping with designing a scalable,
flexible environment, CHAP allows rapid deployment and discovery of volumes with a single ACL entry. For
example, Cluster A could have a single CHAP entry to talk to all of its volumes while Cluster B has a different
single CHAP entry to talk to all of its volumes. Shared volumes such as templates or shared data would have
both Cluster A CHAP and Cluster B CHAP assigned to it dramatically decreasing the administration of ACL
lists.