IBM totalstorage fastt100, Installation, User And Maintenance Manual, Page: 97 / 160

See the Storage Manager client documentation for information on setting cache
memory options.
The RAID controller has a Cache active LED that displays the current status of the
cache. The LED is on if there is data in the cache, and it is off if there is no data in
the cache.
If caching is enabled and the Cache active LED never comes on during I/O activity,
it indicates that the cache memory has failed or the battery has failed (the green
Battery LED will be off).
Note: Always use the Storage Manager client to check your cache memory
settings before assuming a hardware failure.
Figure 53 shows the location of the Cache active LED on the front of the RAID
controller.
RAID controller cache battery
Each RAID controller contains a sealed, rechargeable 4-volt lead-acid battery. This
battery provides cache backup for up to three days in the event of a power loss.
The service life of the battery is three years, after which time the battery must be
replaced. See the Storage Manager client for information on how to view and set
the battery expiration date.
Each RAID controller has a green Battery LED on the back that indicates the
battery status, as follows:
v
The LED is on and remains steady when the battery is fully charged.
v The LED flashes when the battery is charging or performing a self-test.
v
The LED is off if the battery or the battery charger has failed.
The battery performs a self-test at startup and every 25 hours thereafter (during
which time the Battery LED flashes). If necessary, the battery begins recharging at
that time. If the battery fails the self-test, the Battery LED turns off, indicating a
battery fault.
Data caching starts after the battery completes the startup tests.
Cache
active
LED
f10ug036
Figure 53. Cache active LED
Chapter 4. Operating the storage server
67