Batteries
Each node canister in a system contains a battery that provides sufficient power to the node canister to allow an orderly shutdown in the event of a loss of power and prevents the possible cause of damage on the system due to power supply interruptions. If the power to a node canister fails, it can write the configuration state and cache state to the internal drive using the power provided by the battery.
The battery is maintained in a charged state by the battery subsystem. In this state, the battery can save critical data and state information in two back-to-back power failures. This means that the node canister can start immediately after the first power failure without waiting to recharge. After rebooting, if the battery does not have enough charge for a node to save its internal state, the node remains in service until the battery is charged sufficiently.
The battery system supports a 5 second ride-through capability to handle a brief AC power outage of up to 5 seconds. During this brief outage, the battery powers the node, which continues running normally. During this ride-through phase, the node can withstand these brief power outages and can remain available to service host I/O requests. If AC power is restored within the ride-through period, the node continues running normally and does not shut down.
A battery loses its capacity to hold a full charge as it ages. When the system detects that the battery does not have sufficient charge to perform two "fire hose" dumps, a near-end of life event is logged. A near-end of life event is not fatal and the node or node canister remains online. When the system detects that the battery does not have sufficient charge to perform a single "fire hose" dump, an end of life event is logged. An end of life event is fatal. The node or node canister enters the service state and the battery must be replaced.
To access information about the battery in the management GUI, select . On the System - Overview page, click the directional arrow next to the enclosure that contains the battery module. Select Battery Module under Internal Components to display information about the battery module. To display information about the battery in the command-line interface, use the lsenclosurebattery command.