DMP allows you to turn off I/O for a controller or the array port of a storage processor so that you can perform administrative operations. This feature can be used for maintenance of HBA controllers on the host, or array ports that are attached to disk arrays supported by VxVM. I/O operations to the controller or array port can be turned back on after the maintenance task is completed. You can accomplish these operations using the
vxdmpadm command provided with VxVM.
In Active/Active type disk arrays, VxVM uses a balanced path mechanism to schedule I/O to multipathed disks. As a result, I/O may go through any available path at any given point in time. For example, if a system has an Active/Active storage array, and you need to change an interface board that is connected to this disk array (if supported by the hardware), you can use the
vxdmpadm command to list the controllers that are connected to the interface board. Disable the controllers to stop further I/O to the disks that are accessed through the interface board. You can then replace the board without causing disruption to any ongoing I/O to disks in the disk array.
In Active/Passive type disk arrays, VxVM schedules I/O to use the primary path until a failure is encountered. To change the interface card for an array port or an HBA controller card on the host (if supported by the hardware) that is connected to the disk array, disable I/O operations to the array port or to the HBA controller. This shifts all I/O over to an active secondary path or to an active primary path on another controller so that you can change the hardware.
After the operation is over, you can use
vxdmpadm to re-enable the paths through the controllers.
See Disabling I/O for paths, controllers or array ports.
See Enabling I/O for paths, controllers or array ports.
See Upgrading disk controller firmware.
Note From release 5.0 of VxVM, these operations are supported for controllers that are used to access disk arrays on which cluster-shareable disk groups are configured.