
5–6
HSG80 Array Controller V8.7 Maintenance and Service Guide
Upgrading the Subsystem
9. Clear any unit with PREFERRED_PATH set, using the following command as
required for each unit:
HSGA> SET unit-name NOPREFERRED_PATH
10. Disable writeback caching on all units using the following command as required
for each unit:
HSGA> SET unit-name NOWRITEBACK_CACHE NOREADAHEAD_CACHE
NOREAD_CACHE
NOTE: The XXX_CACHE switches must be entered in the specified order or the command
will be rejected.
11. Determine if all data has been flushed from the cache module using the following
command:
HSGA> SHOW THIS_CONTROLLER
The following text is only a portion of the resulting display—an arrow points to the
pertinent status indication:
IMPORTANT: Repeat step 11 on both controllers (THIS_CONTROLLER and
OTHER_CONTROLLER) until no unwritten data remains in either cache module memory.
If unwritten data is present after several minutes, verify that WRITEBACK_CACHE was
disabled on all units using the SHOW UNITS FULL command. For any units with
WRITEBACK_CACHE enabled, return to step 10 and proceed.
12. Shut down Controller B using the following command:
HSGA> SHUTDOWN OTHER_CONTROLLER
IMPORTANT: Disregard any messages pertaining to misconfigured controllers or failover
status.
NOTE: After Controller B shuts down, the reset button and the first three LEDs turn O
N
(see Figure 5–2).
Proceed only after the reset button stops F
LASHING
and remains O
N
.
Cache:
256 megabyte write cache, version 0022
Cache is GOOD
No unflushed data in cache
CACHE_FLUSH_TIMER=1 SECOND