LED Descriptions
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DataDirect Networks EF4024 FC RAID System Setup Guide | 51
A.4.1
Cache Status LED Details
If the LED is flashing steadily, 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
supercapacitor pack provides backup power to flush (copy) data from write cache to
CompactFlash memory. When cache flush is complete, the cache transitions into self-refresh
mode.
If the LED is flashing 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 to 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 time-out 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 CompactFlash, 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 controller cache and one in CompactFlash of each
controller. The Cache Status LED illuminates solid green during the boot-up process. This
behavior indicates the cache is logging all POSTs, which will be flushed to the CompactFlash
the next time the controller shuts down.
CAUTION !
If the Cache Status LED illuminates solid green and you wish to shut
down the controller, this should be done from the user interface, so
unwritten data can be flushed to CompactFlash.
Fault/Service
Required
Amber
On
A fault has been detected or a service action is required
Flashes
Hardware-controlled power-up or a cache flush or
restore error
Cache Status
Green
On
Cache is dirty (contains unwritten data) and operation is
normal. The unwritten information can be log or debug
data that remains in the cache, so a Green cache status
LED does not, by itself, indicate that any user data is at
risk or that any action is necessary.
Off
In a working controller, cache is clean (contains no
unwritten data). This is an occasional condition that
occurs while the system is booting.
Flashes
A CompactFlash flush or cache self-refresh is in
progress, indicating cache activity (See Section
A.4.1
)
Expansion Port
Status
Off
The port is empty or the link is down
On
The port is connected and the link is up
Table 8. Controller Module LED Descriptions
LED
Color
Status
