Battery Operation For Storwize V7000 Unified Gen1 Control Enclosures - IBM Storwize V7000 Unified Problem Determination Manual

Reconditioning the Storwize V7000 Gen2 battery
Reconditioning the battery ensures that the system can accurately determine the
charge in the battery.
As a battery ages, it loses capacity. When a battery no longer has capacity to
protect against two power loss events, it reports the battery end of life event and it
should be replaced.
A reconditioning cycle is automatically scheduled to occur approximately once
every three months, but reconditioning is rescheduled or canceled if the system
loses redundancy. In addition, a two-day delay is imposed between the recondition
cycles of the two batteries in one enclosure.
Battery operation for Storwize V7000 Unified Gen1 control
enclosures
Storwize V7000 Unified node canisters cache volume data and hold state
information in volatile memory.
If the power fails, cache and state data is written to a local flash drive in the
canister. The batteries within the control enclosure provide the power to write the
cache and state data to a local drive.
Note: Storwize V7000 Unified 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 expansion enclosure restarts without operator intervention.
Two power supply units exist in the control enclosure. Each one contains an
integrated battery. Both power supply units and batteries provide power to both
control canisters. Each battery has sufficient charge to save critical data from both
node canisters to the local drive. A fully redundant system has two batteries and
two canisters. In such a system, the batteries can save critical data and state
information from both canisters to a local drive twice. In a system with a failed
battery, there is enough charge in the remaining battery to support saving critical
data from both canisters to a local drive once.
Without ac power, a canister starts saving critical data to a local drive
approximately 10 seconds after it detects the loss. If power is restored within the
10 seconds, the system continues to operate. This loss in power is called a brown
out. When it saves critical data, the system stops handling I/O requests from host
applications. At the same time, Metro Mirror and Global Mirror relationships go
offline. The system powers off after it saves the critical data.
If both node canisters shut down without writing the cache and state data to the
local drive, the system is unable to restart without an extended service action. The
system configuration must be restored. If any cache write data is lost, volumes
must be restored from a backup. It is, therefore, important not to remove the
canisters or the power supply units from the control enclosures unless directed to
do so by the service procedures. Removing either of these components might
prevent the node canister from writing its cache and state data to the local drive.
When the ac power is restored to the control enclosure, the system restarts without
operator intervention. How quickly it restarts depends on whether there is a
history of previous power failures.
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Storwize V7000 Unified: Problem Determination Guide 2073-720