RAID Array 410 HSZ40 HSOF Software Version 3.7 for Compaq Tru64 UNIX Release Notes

Release Notes
AA–RMBXA − TE Page 19
5.2.4 Extending the Life of the External Cache Batteries
Occasionally, circumstances will require you to shut down your controller and
restart it. If the correct steps for turning off power to an HSZ40 array controller
configuration with write-back cache are not followed, there is potential for loss
of data that may exist on any devices connected with them. In addition, if you
are turning off the power to the controller subsystem for any reason for longer
than 1 day (such as a holiday, system move, or replacing a bad SCSI host
cable), you will need to turn off the external cache batteries (ECBs) to prevent
them from discharging. To avoid problems when the controller restarts, always
use the following process to shut it down:
CAUTION
Allowing the write-back cache batteries to discharge completely,
and leaving them in a discharged state for any length of time,
could result in permanent and irreversible degradation to the
batteries.
5.2.4.1 Shutting Down a Controller
1.
Use the proper procedures for shutting down the operating system if the
host system is also going to be turned off.
2.
If the host is not going to be turned off, it is not necessary to shut down the
host system, but use the proper operating system procedures to dismount
any units that are accessed through the HSZ40 array controllers.
3.
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
drain, causing the data in the cache modules to be lost. If you have
RAIDset or mirrorset units, or single devices with write-back caching
turned on,
SET NORUN on all units.
4.
When the dismount and/or the operating system shutdown procedures are
complete, invoke the controller
SHUTDOWN commands on the controllers.