Cache Status Led - Power On Behavior - HP MSA 2050 User Manual

NOTE: Once a Link Status LED is lit, it remains so, even if the controller is shutdown via the SMU or CLI.
When a controller is shutdown or otherwise rendered inactive—its Link Status LED remains illuminated—falsely
indicating that the controller can communicate with the host. Though a link exists between the host and the chip on the
controller, the controller is not communicating with the chip. To reset the LED, the controller must be properly
power-cycled [see
Cache Status LED details
Power on/off behavior
The storage enclosure's unified CPLD provides integrated Power Reset Management (PRM) functions. During power on,
discrete sequencing for power on display states of internal components is reflected by blinking patterns displayed by the
Cache Status LED (see
Table 26 Cache Status LED – power on behavior
Item
Display state
Component
Blink pattern
Once the enclosure has completed the power on sequence, the Cache Status LED displays Solid/On (Normal), before
assuming the operating state for cache purposes.
Cache status behavior
If the LED is blinking evenly, a cache flush is in progress. When a controller module loses power and write cache 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 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 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—do so from the
user interface, so unwritten data can be flushed to CompactFlash.
Power supply LEDs
Power redundancy is achieved through two independent load-sharing power supplies. In the event of a power supply
failure, or the failure of the power source, the storage system can operate continuously on a single power supply. Greater
redundancy can be achieved by connecting the power supplies to separate circuits. DC power supplies are equipped with
a power switch. AC power supplies do not have a power switch. Whether a power supply has a power switch is significant
to powering on/off. Power supplies are used by controller and drive enclosures.
"Powering on/powering off" (page
Table 26).
Display states reported by Cache Status LED during power on sequence
0 1
VP SC
On 1/Off 7 On 2/Off 6 On 3/Off 5 On 4/Off 4 On 5/Off 3 On 6/Off 2
22)].
2 3
SAS BE ASIC
4 5
Host Boot Normal
Solid/On
6 7
Reset
Steady
Rear panel LEDs 69