Automatic load balancing provides improved I/O resource management by reacting dynamically to load changes over time and automatically adjusting volume controller ownership to correct any load imbalance issues when workloads shift across the controllers.
The workload of each controller is continually monitored and, with cooperation from the multipath drivers installed on the hosts, can be automatically brought into balance whenever necessary. When workload is automatically re-balanced across the controllers, the storage administrator is relieved of the burden of manually adjusting volume controller ownership to accommodate load changes on the storage array.
Automatic Load Balancing is enabled by default on all storage arrays.
Even though Automatic Load Balancing is enabled at the storage array level, the host type you select for a host or host cluster has a direct influence on how the feature operates.
When balancing the storage array's workload across controllers, the Automatic Load Balancing feature attempts to move volumes that are accessible by both controllers and that are mapped only to a host or host cluster capable of supporting the Automatic Load Balancing feature.
This behavior prevents a host from losing access to a volume due to the load balancing process; however, the presence of volumes mapped to hosts that do not support Automatic Load Balancing affects the storage array's ability to balance workload. For Automatic Load Balancing to balance the workload, the multipath driver must support TPGS and the host type must be included in the following table.
Host type supporting Automatic Load Balancing | With this multipath driver |
---|---|
Windows or Windows Clustered | MPIO with NetApp E-Series DSM |
Linux DM-MP (Kernel 3.10 or later) | DM-MP with scsi_dh_alua device handler |
VMware | Native Multipathing Plugin (NMP) with VMW_SATP_ALUA Storage Array Type plug-in |
See the Interoperability Matrix Tool for compatibility information for specific multipath driver, OS level, and controller-drive tray support.
Verify OS compatibility with the Automatic Load Balancing feature before setting up a new (or migrating an existing) system.
If your system is running Red Hat Enterprise Linux 6 or SUSE Linux Enterprise Server 11, refer to Knowledge base article 1015843