VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Enabling and Disabling Input/Output (I/O) Controllers
98 VERITAS Volume Manager Administrator’s Guide
If a ’*’ follows VID, it will result in the inclusion of all disks
returning Vendor ID starting with the specified VID. The same is
true for Product ID as well. Both VID and PID should be non NULL.
The maximum allowed lengths for Vendor ID and Product ID are 8 and
16 characters respectively.
Some examples of VID:PID specification are:
all - Exclude all disks
aaa:123 - Exclude all disks having VID ‘aaa’ and PID ‘123’
aaa*:123 - Exclude all disks having VID starting with ‘aaa’
and PID ‘123’
aaa:123* - Exclude all disks having VID ‘aaa’ and PID starting
with ‘123’
aaa:* - Exclude all disks having VID ‘aaa’ and any PID
Enter a VID:PID combination:[<pattern>,all,list-exclude,q,?]
Enabling and Disabling Input/Output (I/O) Controllers
DMP allows you to turn off I/O to a host I/O controller so that you can perform
administrative operations. This feature can be used for maintenance of controllers
attached to the host or of disk arrays supported by VxVM. I/O operations to the host I/O
controller 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 usesa balanced pathmechanism toschedule 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 host I/O controllers that are
connected to the interface board. Disable the host I/O 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 an interface card on the disk array or a card on the host
(if supported by the hardware) that is connected to the disk array, disable I/O operations
to the host I/O controllers. This shifts all I/O over to an active secondary path or to an
active primary path on another I/O 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.