Each node canister in the control enclosure caches critical
data and holds state information in volatile memory.
If power to a node canister fails, the
node canister uses battery power to write cache and state data to
its boot drive.
Note: Lenovo Storage V7000 Gen2 expansion
canisters do not cache volume data or store state information in volatile
memory. Therefore, expansion canisters do not require battery power.
If ac power to both power supplies in an expansion enclosure fails,
the enclosure powers off. When ac power is restored to at least one
power supply, the enclosure restarts without operator intervention.
The battery is maintained in a fully charged state by
the battery subsystem. At maximum power, the battery can save critical
data and state information in two back-to-back power failures. If
power to a node canister is lost, saving critical data starts after
a five-second wait. (If the outage is shorter than five seconds, the
battery continues to support the node and critical data is not saved.)
The node canister stops handling I/O requests from host applications.
The saving of critical data runs to completion, even if power is restored
during this time. The loss of power might be because the input power
to the enclosure is lost, or because the node canister is removed
from the enclosure.
When power is restored to the
node canister, the system restarts without operator intervention.
How quickly it restarts depends on whether there is a history of previous
power failures. The system restarts only when the battery has sufficient
charge for the node canister to save the cache and state data again.
A node canister with multiple power failures might not have sufficient
charge to save critical data. In such a case, the system starts in
service state and waits to start I/O operations until the battery
has sufficient charge.
Two light-emitting diode (LED) indicators
indicate the state of the battery:
- Status LED - Green
- Fault LED - Amber
See
"Procedure: Understanding the system status from the Lenovo Storage V7000 Gen2 LEDs" for
a complete description of the battery LEDs.
Important: Although Lenovo Storage V7000 Gen2 is
resilient to power failures and brown outs, always install Lenovo Storage V7000 Gen2 in
an environment with reliable, consistent, and required ac power. Consider
uninterruptible power supply units to avoid extended interruptions
to data access.
Design parameters
Consider the following
important design parameters:
- The design life of the battery in the Lenovo Storage V7000 Gen2 is
five years service after one year on the shelf.
- Each battery is automatically reconditioned every
three months to measure the battery capacity. Batteries in the same
enclosure are not reconditioned within two days of each other. If
a battery has a lower capacity than required (below the planned threshold),
it is marked as "End Of Life" and should be replaced.
- Each battery provides power only for the canister
in which it is installed. If a battery fails, the canister goes offline
and reports a node error. The single running canister destages its
cache and runs the I/O group in "write-through" mode until its
partner canister is repaired and online.