To allow concurrent maintenance, SAN Volume Controllers must be configured in pairs.
While one SAN Volume Controller is being serviced, the other keeps the I/O group operational. With concurrent maintenance, all field-replaceable units (FRUs) can be removed, replaced, and tested on one SAN Volume Controller while the SAN and host systems are powered on and doing productive work.
Attention: Do not remove the power from both SAN Volume Controllers unless the procedures instruct you to do so.
Confirm that no hosts have dependencies on the node.
When shutting down a node that is part of a cluster, or when deleting the node from a cluster, use the Show Dependent VDisks menu option on the Viewing Nodes panel in the SAN Volume Controller Console to display all the VDisks that are dependent on a node, or use the svcinfo lsnodedependentvdisk command to view dependent VDisks.
If dependent VDisks exist, determine if the VDisks are being used. If the VDisks are being used, either restore the redundant configuration or suspend the host application. If a dependent quorum disk is reported, repair the access to the quorum disk or modify the quorum disk configuration.
Some host multipathing device drivers take a while to update after changes are made on the fabric. Do not shut down a node or delete the node from a cluster if the partner node in the I/O group to which the node belongs has not been online for more than 30 minutes.
If possible, check the status of the host multipathing device drivers before shutting down a node to ensure that the device drivers can fail over to the partner node.
When shutting down the node, see MAP 5350: Powering off a SAN Volume Controller node for a description of how to check for dependencies on the node during the procedure to turn off the node.
When deleting a node from the cluster, see Deleting a node from a cluster using the SAN Volume Controller Console for a description of node information to retain to avoid data corruption when adding the node back to the cluster, how to ensure that the multipathing device driver does not rediscover any paths that are manually removed, and for other considerations regarding dependent VDisks.