HP Array Controller HSG V8.7 Software - Manual (Page 53)

General Description 1–29
When the batteries are fully charged, an ECB can preserve 512 MB of
cache memory for 24 hours. However, the battery capacity depends
upon the size of memory contained in the cache module, as defined in
the Table 1–9.
Table 1–9 ECB Capacity Based on Memory Size
Charging Diagnostics
Whenever you restart the controller, its diagnostic routines
automatically check the charge in the ECB’s batteries. If the batteries
are fully charged, the controller reports them as good and rechecks
them every 24 hours. If the batteries are charging, the controller
rechecks them every four minutes. Batteries are reported as being either
above or below 50 percent in capacity. Batteries below 50 percent in
capacity are referred to as being low.
This four-minute polling continues for up to 10 hours—the maximum
time it should take to recharge the batteries. If the batteries have not
been charged sufficiently after 10 hours, the controller declares them to
be failed.
Battery Hysteresis
When charging a battery, write-back caching will be allowed as long as
a previous down time has not drained more than 50 percent of a
battery’s capacity. When a battery is operating below 50 percent
capacity, the battery is considered to be low and write-back caching is
disabled.
Caution DIGITAL recommends that you replace the ECB every two
years to prevent battery failure.
Size DIMM Combinations Capacity
64 MB Two, 32 MB 96 hours
128 MB Four, 32 MB 48 hours
256 MB Two, 128 MB 48 hours
512 MB Four, 128 MB 24 hours