Release Notes

Advanced iSCSI connection configuration parameters
15 Configuring and Installing the PS Series Multipathing Extension Module for VMware vSphere and PS Series | TR1074
6 Advanced iSCSI connection configuration parameters
The few configuration parameters that are needed with the MEM are used to alter the runtime behavior of the
EqualLogic Host Connection Manager (EHCM) that manages the iSCSI sessions to the PS Series volumes.
For information on all of the parameters, refer to the EqualLogic Multipathing Extension Module Installation
and User Guide.
Three configuration parameters affect the number of iSCSI sessions created:
• totalsessions: The maximum total number of sessions that may be created on all PS Series volumes
accessible to the host. The default value is 512.
• volumesessions: The maximum number of sessions that may be created on an individual PS Series
volume. The default value is 6.
• membersessions: The maximum number of session that may be created on the portion of a volume
that resides on a single member. The default value is 2.
When determining how many sessions to create, EHCM chooses a value that meets all these constraints.
The default values provide good performance without unnecessarily consuming excess resources. In the
majority of installations, these settings do not need to be changed from the defaults.
Prior to altering these values, it is strongly advised that an administrator fully understand the impact of such a
change on the total number of iSCSI connections. For information on the number of iSCSI connections that
particular firmware versions can handle at a per pool and group level, refer to the release notes for that
firmware. Refer to the applicable VMware documentation for details on vSphere limits that may apply.
Section 2.2, Deployment considerations for iSCSI connection count, includes a formula for calculating the
iSCSI connection count based on the number of hosts, sessions per volume portion, PS Series members in
the pool, and the number of volumes the hosts are connected to. Take into account connections from other
systems in the total iSCSI connection count such as:
• Other physical servers
• Virtual machines with iSCSI within the guest connections
• Backup servers
• Short-lived connections which are used by the vSphere VAAI Full Copy primitive and replication
6.1 Increasing the default values
In some lab settings, it may be necessary to increase the number of iSCSI connections for benchmarking I/O
to an individual volume or to test the limits.
In such a configuration, it is possible that the default membersession value is limiting the number of iSCSI
connections to fewer than the number of VMkernel ports bound to the iSCSI initiator. To utilize all the
VMkernel ports bound to the iSCSI initiator, increase membersessions sufficiently to enable EHCM to create
iSCSI connections through all bound VMkernel ports.
Generally, this increase would not be beneficial in a production environment. In a production environment,
multiple volumes are used, and EHCM would, in aggregate, create and balance an optimal number of iSCSI
sessions to effectively utilize all of the network ports.