IBM System Storage DS3000, Руководство по программированию

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designated when the logical drive is created. If the preferred controller is being replaced or undergoing a
firmware download, ownership of the logical drives is automatically shifted to the other controller. That
controller becomes the current owner of the logical drives. This change is considered to be a routine
ownership change and is reported in the Event Log.
To redistribute logical drives to their preferred controllers, use this command:
reset storageSubsystem logicalDriveDistribution
Important: If you run this command without a multi-path driver on the hosts, stop I/O activity to the
logical drives to prevent application errors.
Important:
You cannot run this command if all of the logical drives are currently owned by their
preferred controller, or the storage subsystem does not have defined logical drives.
Under some host operating systems, you must reconfigure the multi-path host driver. You might also
need to make operating system modifications to recognize the new I/O path to the logical drive.
Replacing CRUs
The DS3950, DS3000, DS4000, DS5000, and DS5020 controller module components, such as the controller
CRUs, the power-fan CRUs, and the interconnect-battery CRUs, have a Service Action Allowed (SAA)
indicator light. This indicator light is a blue LED. The Service Action Allowed indicator light helps to
make sure that you do not remove a CRU before it is safe to do so.
Attention: Possible loss of data access – Never remove a component that has a Service Action
Required indicator light on unless the Service Action Allowed (SAA) indicator light is on.
If a component fails and must be replaced, the Service Action Required indicator light on that CRU
comes on to indicate that service action is required, provided no data availability dependencies or other
conditions exist that dictate the CRU should not be removed. The Service Action Allowed indicator light
automatically comes on or goes off when conditions change. In most cases, the Service Action Allowed
indicator light comes on steadily when the Service Action Required indicator light comes on for the CRU.
If the interconnect-battery CRU must be replaced, the Service Action Allowed indicator light does not
come on automatically. Before the Service Action Allowed indicator light on the interconnect-battery CRU
can come on, you must place controller CRU in slot B into Service mode. This action routes all control
and I/O activity through one controller to help make sure that data access is maintained while the
interconnect-battery CRU is removed. The Service Action Allowed indicator light comes on after the new
CRU has been installed.
The ability to remove a CRU depends on the data availability dependencies of the controller module or
the controller module. The Service Action Allowed indicator light does not come on if removing a CRU
jeopardizes data on the expansion drawers or current I/O activity. An example of limiting when you can
remove a CRU is when one controller CRU has a Service Action Required indicator light on. You cannot
remove the other controller CRU (the Service Action Allowed indicator light does not come on), because
doing so would jeopardize the data either on the expansion drawers or migrating through the controllers.
A less obvious example, as in the DS4800 storage subsystem, is when the power supply for the controller
CRU in slot A has failed, and the controller CRU in slot B has failed. Removing the controller CRU in slot
B before replacing the failed power-fan CRU causes the controller CRU in slot A to lose power, which
results in a loss of data access. This action occurs because power distribution from each power-fan CRU
is through the controller CRU that is physically connected to that power-fan CRU.
So, in the preceding example, these actions occur:
v
The power-fan CRU has both its Service Action Required indicator light and its Service Action Allowed
indicator light on.
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IBM System Storage DS3000, DS4000, and DS5000: Command Line Interface and Script Commands Programming Guide