Maintenance Discharge Cycles - IBM Storwize V7000 Troubleshooting And Maintenance Manual

A battery is considered failed for the following conditions:
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4 v When the system can communicate with it and it reports an error.
4 v 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
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a manner that makes communication with the battery impossible.
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There are conditions other than loss of ac power that can cause critical data to be saved and the nodes to
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go into service state and not permit I/O operations. The node canisters save critical data if they detect
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4 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
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enclosure is sufficient to support a saving of critical data once; therefore, both canisters are in active state
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4 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
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4 of the critical data if the ac power fails. Data protection cannot be guaranteed in this case. The nodes save
4 the critical data 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
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4 has sufficient charge, the system automatically restarts.
Important: Although Storwize V7000 is resilient to power failures and brown outs, always install
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4 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
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interruptions to data access.
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Maintenance discharge cycles

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Perform periodic maintenance discharges to extend the lifetime of the batteries and to ensure that the
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system can accurately measure the charge in the batteries.
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Periodic maintenance discharges also guarantee that the batteries have sufficient charge to protect the
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system.
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Maintenance discharge cycles are scheduled automatically by the system and involve fully discharging a
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battery and then recharging it again. Maintenance discharges are normally scheduled only when the
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4 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.
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This condition also ensures that I/O operations continue while the maintenance cycle is performed. It is
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4 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
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4 completes, the maintenance on the other battery starts.
Maintenance discharges are scheduled for the following situations:
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v A battery has been powered on for three months without a maintenance discharge.
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4 v A battery has provided protection for saving critical data at least twice.
4 v A battery has provided protection for at least 10 brown outs, which lasted up to 10 seconds each.
A maintenance discharge takes approximately 10 hours to complete. If the ac power outage occurs during
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4 the maintenance cycle, the cycle must be restarted. The cycle is scheduled automatically when the battery
is fully charged.
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4 Under the following conditions, a battery is not considered when calculating whether there is sufficient
charge to protect the system. This condition persists until a maintenance discharge cycle is completed.
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v A battery is performing a maintenance discharge.
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4 v A battery has provided protection for saving critical data at least four times without any intervening
maintenance discharge.
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Storwize V7000 Version 6.1.0: Troubleshooting, Recovery, and Maintenance Guide