IBM Storwize V7000 Maintenance Manual Download

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completed charging, then the system starts in service state and does not permit
I/O operations to be restarted until the batteries are half charged. The recharging
takes approximately 30 minutes.

In a system with a failed battery, an ac power failure causes both canisters to save
critical data and completely discharges the remaining battery. When the ac power
is restored, the system starts in service state and does not permit I/O operations to
be restarted until the remaining battery is fully charged. The recharging takes
approximately 1 hour.

A battery is considered failed for the following conditions:

When the system can communicate with it and it reports an error.

When the system is unable to communicate with the battery. Failed
communication exists because the power supply, which contains the battery, has
been removed or because the power supply has failed in a manner that makes
communication with the battery impossible.

There are conditions other than loss of ac power that can cause critical data to be
saved and the nodes to go into service state and not permit I/O operations. The
node canisters save critical data if they detect there is no longer sufficient battery
charge to support a saving of critical data. This situation happens when, for
example, both batteries have two-thirds of a charge. The total charge that is
available in the enclosure is sufficient to support a saving of critical data once;
therefore, both canisters are in active state and I/O operations are permitted. If one
battery fails though, the remaining battery has only two-thirds of a charge, and the
total charge that is available in the enclosure is now insufficient to perform a
saving of the critical data if the ac power fails. Data protection cannot be
guaranteed in this case. The nodes save the critical data by using the ac power and
enter service state. The nodes do not handle I/O operations until the remaining
battery has sufficient charge to support the saving of the critical data. When the
battery has sufficient charge, the system automatically restarts.

Important:

Although Storwize V7000 is resilient to power failures and brown

outs, always install Storwize V7000 in an environment where there is reliable and
consistent ac power that meets the Storwize V7000 requirements. Consider
uninterruptible power supply units to avoid extended interruptions to data access.

Maintenance discharge cycles

Maintenance discharge cycles extend the lifetime of the batteries and ensure that
the system can accurately measure the charge in the batteries. Discharge cycles
guarantee that the batteries have sufficient charge to protect the Storwize V7000
system.

Maintenance discharge cycles are scheduled automatically by the system and
involve fully discharging a battery and then recharging it again. Maintenance
discharges are normally scheduled only when the system has two fully charged
batteries. This condition ensures that for the duration of the maintenance cycle, the
system still has sufficient charge to complete a save of the critical data if the ac
power fails. This condition also ensures that I/O operations continue while the
maintenance cycle is performed. It is usual for both batteries to require a
maintenance discharge at the same time. In these circumstances, the system
automatically schedules the maintenance of one battery. When the maintenance on
that battery completes, the maintenance on the other battery starts.

Storwize V7000: Troubleshooting, Recovery, and Maintenance Guide