Compaq StorageWorks HSZ80 Configuration And Cli Reference Manual page 283

The following tasks are performed when the NOMIRRORED_CACHE switch is
specified: Both controllers must be operational before this command is accepted.
Data in write-back cache is flushed when cache is configured in non-mirrored
mode.
Enables mirrored write-back cache on both controllers.
If an invalid cache configuration exists within the cache modules, an error is
generated.
Issue this switch through only one controller. The controller must contain a valid
cache configuration before specifying this switch. See Chapter 2 for rules regarding
valid cache configurations. The controllers automatically restart when this switch is
specified.
NOTE: All unwritten write-cached data is automatically flushed from cache before
restart when the MIRRORED_CACHE switch is specified. Depending on the amount
of data to be flushed, this command may take several minutes to complete before
the controller is restarted.
The NOMIRRORED_CACHE switch disables mirror mode. Data in write-back
cache is flushed when this switch is entered from mirrored mode. This switch disables
mirrored write-back cache on both controllers. Therefore, this switch is only to be
issued through one controller. The controller must contain a valid cache configuration
before this switch is assigned. Unlike going from nonmirrored mode to mirrored
mode, going from mirrored mode to nonmirrored mode is permitted with a failed
cache module. The controller automatically restarts when this switch is specified.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
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