HP AA988A - Modular Smart Array Storage Controller SCSI, User Manual

Page: 19 / 102

Chapter 1 System Components 19
Controller
module Cache status Green Blink A Compact Flash flush or cache self-refresh
is in progress. Indicates cache activity.
• If the LED is blinking evenly, a cache
flush is in progress. When a controller
module loses power and write cache is
dirty (contains data that has not been
written to disk), the super-capacitor pack
provides backup power to flush (copy)
data from write cache to Compact Flash
memory. When cache flush is complete,
the cache transitions into self-refresh
mode.
• If the LED is blinking slowly, a cache
flush is in progress. In self-refresh mode,
if primary power is restored before the
backup power is depleted (3
–
30 minutes,
depending on various factors), the system
boots, finds data preserved in cache, and
writes it to disk. This means the system
can be operational within 30 seconds, and
before the typical host I/O timeout of 60
seconds at which point system failure
would cause host-application failure. If
primary power is restored after the backup
power is depleted, the system boots and
restores data to cache from Compact
Flash, which can take about 90 seconds.
Note : The cache flush and self-refresh
mechanism is an important data protection
feature; essentially four copies of user data
are preserved: one in each controller’s cache
and one in each controller’s Compact Flash.
Controller
module Host activity Green Off The host ports have no I/O activity.
Blink At least one host port has I/O activity.
Controller
module Ethernet link status Green Off The Ethernet port is not connected or the
link is down.
On The Ethernet link is up.
Table 1-5 Controller LEDs (Back) (Continued)
Location LED Color State Description