HP StorageWorks 2324fc, User Manual

Page: 39 / 80

HP StorageWorks Carrier-Grade 2324fc Modular Smart Array user guide 35
10 Cache Status Green — Cache is dirty (contains unwritten data) and operation is
normal.
Off — In a working controller, cache is clean (contains no
unwritten data).
Blinking green — A CompactFlash flush or cache self-refresh is in
progress. Indicates cache activity. (See also If the controller has
failed or does not start, is the Cache Status LED on/blinking? )
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 momentarily slowly, the cache is in a
self-refresh mode. 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.
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 CompactFlash.
11 Host Activity Blinking green — At least one host port has I/O activity.
Off — Host ports have no activity.
LED Description Definition