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SMART TEST=ON enables the test bit in the Information exception mode page for all the disks installed.
Setting the test bit simulates a FALSE SMART trip condition which raises a FALSE check condition to
the controller. Currently, this parameter is valid only with Fibre Channel disks.
SMART TEST=OFF disables the test bit in the Information exception mode page for all the disks
installed.
SMART INTERVALTIME displays the interval (in hours) in which the SMART Information will be
polled.
SMART INTERVALTIME=h sets the interval (in hours) that SMART Information polling will occur. 'h'
indicates the interval in hours in the range <1..24>.
3.2.12 Couplet Controller Configuration (Cache/Non-Cache Coherent)
There are two primary couplet controller configurations: cache coherent and non-cache coherent.
The DUAL command displays information about couplet system configuration
(Figure 3–27).
Figure 3–27 Couplet Controller Configuration
3.2.12.1 Cache Coherent
In this configuration, each controller can access all LUNs. The couplet controller communication occurs
over the internal UART and private Ethernet. If the controllers detect an Ethernet failure, controller 2
will be failed. (This means that an external event can cause a controller to fail even though the controller
may be perfectly fine.) Therefore, it is mandatory that the controller Ethernet resides on a private
Ethernet segment.
NOTE :
Data cache is not copied from one controller to another. If a controller fails, all “dirty”
data in cache will be lost. Thus if power failures are a concern, writeback cache should
be disabled.
Non-Cache Coherent
In this configuration, the couplet controller communication occurs over the internal UART. Each
controller owns LUNs and tiers. Spare drives are “owned” by individual controller units, according to
tier ownership.
In healthy situations, the controller cannot access LUNs or tiers owned by the other controller. However,
if the other controller is failed, the healthy controller will have access to all LUNs and tiers.
Users, via mapping, can be assigned any combination of LUNs. In a healthy environment, users will only
see LUNs owned by the controller to which they are connected.