5-2 Sun StorEdge 3000 Family Installation, Operation, and Service Manual • May 2004
5.1 Controller Defaults and Limitations
This section describes default configurations and certain controller limitations.
5.1.1 Planning for Reliability, Availability, and
Serviceability
The Sun StorEdge 3510 and 3511 FC array entry-level configurations include only
one controller. You can mirror two single-controller arrays using volume manager
software on attached servers to ensure high reliability, availability, and serviceability
(RAS).
You can also use dual-controller arrays to avoid a single point of failure. A dual-
controller array features a default active-to-active controller configuration. This
configuration provides high reliability and high availability because, in the unlikely
event of a controller failure, the array automatically fails over to a second controller,
resulting in no interruption of data flow.
Other dual-controller configurations can be used as well. For instance, at a site
where maximum throughput or connecting to the largest possible number of servers
is of primary importance, you could use a high-performance configuration. Refer to
the Sun StorEdge 3000 Family Best Practices Manual for information about array
configurations.
Be aware, however, that departing from a high-availability configuration can result
in a significant decrease in the mean time between data interruptions. System
downtime, however, is not affected as severely. The time required to replace a
controller, if one is available, is only about five minutes.
Regardless of configuration, customers requiring high availability should stock field-
replaceable units (FRUs), such as disk drives and controllers, on site. Your FC array
has been designed to make replacing these FRUs easy and fast.
5.1.2 Dual-Controller Considerations
The following controller functions describe the redundant controller operation.
â– Both controllers must be exactly the same. They must operate with the same
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
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