HP storageworks HSG80 Reference Manual page 164

CLI Command Descriptions
MAXIMUM_CACHED_TRANSFER_SIZE switch affects both read and
write-back cache when set on a controller that has read and write-back caching.
The use of this switch has the effect of setting both the
MAX_READ_CACHED_TRANSFER_SIZE and the
MAX_WRITE_CACHED_TRANSFER_SIZE switches.
PREFERRED_PATH=OTHER_CONTROLLER
PREFERRED_PATH=THIS_CONTROLLER
NOPREFERRED_PATH (default)
This command is only valid when in MULTIBUS_FAILOVER mode.
The PREFERRED_PATH switch allows you to balance the I/O load by specifying
the controller through which the unit is accessed. If you set
NOPREFERRED_PATH for a unit, it can be accessed through either controller.
The controllers only use the PREFERRED_PATH setting if they are in a
dual-redundant configuration. If one controller fails, all the devices are accessed
through the remaining controller ignoring the PREFERRED_PATH setting.
When the failed controller is restarted, the drives automatically return to the
controller specified by the PREFERRED_PATH switch.
You can specify the PREFERRED_PATH switch for a single controller
configuration; however, the switch will not take effect until you add a second
controller and configure the two controllers for dual-redundancy.
• When no preferred path is assigned, the unit is targeted through the controller
that detects the unit first after the controllers start.
• Select PREFERRED_PATH=THIS_CONTROLLER to instruct "this
controller" to bring the units online.
• Select PREFERRED_PATH=OTHER_CONTROLLER to instruct the "other
controller" to bring the units online.
NOTE: All partitions on a container must be addressed through the same controller. If you set
PREFERRED_PATH for one partition, all partitions on that container inherit the same path.
READ_CACHE (default)
NOREAD_CACHE
If READ_CACHE is selected, when the controller receives a read request from the
host, it reads the data from the disk drives, delivers it to the host, and stores the
data in its cache module. Subsequent reads for the same data will take the data
from cache rather than accessing the data from the disks.
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