HP AA988A HP StorageWorks 2012sa Modular Smart Array user guide (488320-002, J - Page 19

Table 1-5 Controller LEDs (Back) (Continued) Location Controller module Controller module Controller module LED Cache status Host activity Color Green Green State Description 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. Off The host ports have no I/O activity. Ethernet link status Green Blink At least one host port has I/O activity. Off The Ethernet port is not connected or the link is down. On The Ethernet link is up. Chapter 1 System Components 19