Controller Defaults And Limitations; I "Controller Defaults And Limitations - Sun Microsystems StorEdge 3000 Series Installation, Operation And Service Manual

5.1

Controller Defaults and Limitations

The following controller functions describe the redundant controller operation.
Both controllers must be exactly the same. They must operate with the same
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firmware version, the same size of memory, and the same number of host and
drive channels. If one controller in a dual-controller configuration is replaced with
a field-replaceable unit (FRU) controller, the array automatically compares the
firmware versions of the two controllers. If they differ, the FRU controller
firmware is automatically changed to that of the existing controller in the array.
The controller firmware assumes that two controllers are available, or might be
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made available during operation at any time. In a 1U single-controller
configuration, a 2U single-controller configuration, or a 2U dual-configuration,
once the primary controller (which might be the only controller) is powered on, it
begins to scan for a second controller. Until a second controller is discovered,
which does not happen in a 1U single-controller configuration or a 2U single-
controller configuration, the "Peripheral Device Status" for the redundant
controller will show a Status of "Scanning." This is correct behavior and enables
the firmware to discover a second controller whenever it is added without the
necessity of rebooting the primary controller.
In redundant mode, the maximum number of disk drive IDs on a SCSI drive
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channel is 16. IDs 6 and 7 are used for host HBA connections.
After booting in a redundant configuration, the controllers autonegotiate and
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designate one controller as primary and the other controller as secondary.
The two controllers behave as one primary controller. Once the redundant
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configuration takes effect, user configurations and settings can be done only on
the primary controller. The secondary controller then synchronizes with the
configuration of the primary controller, making the configurations of the two
controllers exactly the same.
The two controllers continuously monitor each other. When a controller detects
that the other controller is not responding, the working controller immediately
takes over and disables the failed controller.
It is necessary to connect all interfaces to both controllers so that the surviving
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controller can readily continue all services provided for the RAID system. For
example, if you connect one controller to the Ethernet, you should also connect
the second controller to the Ethernet.
In an active-to-active configuration (standard configuration), you can assign any
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appropriate logical drives to either of the controllers, and then map the logical
configurations to host channel IDs/LUNs. I/O requests from host computer are
directed to the primary or the secondary controller accordingly. The total drive
capacity can be grouped into several logical configurations and equally assigned
to both controllers so that they share the workload.
5-2 Sun StorEdge 3000 Family Installation, Operation, and Service Manual • March 2004