User`s guide

CAUTION
If the correct steps for turning off the power to an HS array controller
configuration with write-back cache are not followed, there is a potential
for loss of data that may exist on any devices connected to the HS array
controllers.
1. Use the proper procedures for shutting down your operating system if the
host system is also going to be turned off.
If the host is not going to be turned off, a shut down of the host system is not
necessary, but use the proper operating system procedures to dismount any
units that are accessed through the HS array controllers.
2. When the dismount and/or the operating system shutdown procedures are
complete, invoke the controller SHUTDOWN commands on the HS array
controllers.
CAUTION
Do not turn off the power to the controller subsystem until all shutdown
procedures have successfully completed.
3. If you have a dual-redundant controller configuration, shutdown each
controller one at a time. If you have a single terminal CLI interface, such as
a VAXcluster Console System (VCS), use the following commands:
CLI> SHUTDOWN OTHER_CONTROLLER
CLI> SHUTDOWN THIS_CONTROLLER
If you have a non-redundant controller configuration, only the SHUTDOWN
THIS_CONTROLLER command is necessary.
4. Only when the controller SHUTDOWN command has successfully completed,
should you turn off power to the controller subsystem (or just the controller
shelf, if you are not shutting down the entire system, by unplugging the
power supplies in the controller shelf).
5. If the controller configuration contains any devices or storagesets that are
write-back cache enabled, and the system is going to be turned off for an
extended length of time, the batteries on the write-back cache modules will
drain, causing the data in the cache modules to be lost.
5–44 Controller Operations