SAN Volume Controller nodes are powered by an uninterruptible power supply that is located in the same rack as the SAN Volume Controller nodes.
The power state of the SAN Volume Controller is displayed by a power indicator on the front panel. If the uninterruptible power supply battery is not sufficiently charged to enable the SAN Volume Controller to become fully operational, its charge state is displayed on the front panel display of the SAN Volume Controller node.
The power to a SAN Volume Controller is controlled by the power button on the front panel of the SAN Volume Controller node or by commands sent by the Ethernet interface. Never turn off the SAN Volume Controller node by removing the power cable. You might lose data. For more information about how to power off the SAN Volume Controller node, see MAP 5350: Powering off a SAN Volume Controller node.
If the SAN Volume Controller software is running and you request it to power off from the SAN Volume Controller Console, CLI, or power button, the SAN Volume Controller node starts its power off processing. During this time, the SAN Volume Controller node indicates the progress of the power-off operation on the front panel display. After the power-off processing is complete, the front panel becomes blank and the front panel power light flashes. It is safe for you to remove the power cable from the rear of the SAN Volume Controller node. If the power button on the front panel is pressed during power-off processing, the front panel display changes to indicate that the SAN Volume Controller node is being restarted, but the power-off process completes before the restart is performed.
If the SAN Volume Controller software is not running when the front panel power button is pressed, the SAN Volume Controller node immediately powers off.
If you turn off a SAN Volume Controller node using the power button or by a command, the SAN Volume Controller node is put into a power-off state. The SAN Volume Controller remains in this state until the power cable is connected to the rear of the SAN Volume Controller node and the power button is pressed.
During the SAN Volume Controller startup sequence, the SAN Volume Controller tries to detect the status of the uninterruptible power supply through the uninterruptible power supply signal cable. If an uninterruptible power supply is not detected, the SAN Volume Controller node pauses and an error is shown on the front panel display. If the uninterruptible power supply is detected, the software monitors the operational state of the uninterruptible power supply. If no uninterruptible power supply errors are reported and the uninterruptible power supply battery is sufficiently charged, the SAN Volume Controller becomes operational. If the uninterruptible power supply battery is not sufficiently charged, the charge state is indicated by a progress bar on the front panel display. When an uninterruptible power supply is first turned on, it might take up to two hours before the battery is sufficiently charged for the SAN Volume Controller node to become operational.
If input power to the uninterruptible power supply is lost, the SAN Volume Controller node immediately stops all I/O operations and saves the contents of its dynamic random access memory (DRAM) to the internal disk drive. While data is being saved to the disk drive, a Power Failure message is shown on the front panel and is accompanied by a descending progress bar that indicates the quantity of data that remains to be saved. After all the data is saved, the SAN Volume Controller node is turned off and the power light on the front panel turns off.