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 Lenovo Storage 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 completed. 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.
A maintenance discharge takes approximately 10 hours to complete. If the ac power outage occurs during the maintenance cycle, the cycle must be restarted. The cycle is scheduled automatically when the battery is fully charged.
If a system suffers repeated ac power failures without a sufficient time interval in between the ac failures to complete battery conditioning, then neither battery is considered when calculating whether there is sufficient charge to protect the system. In these circumstances, the system enters service state and does not permit I/O operations to be restarted until the batteries have charged and one of the batteries has completed a maintenance discharge. This activity takes approximately 10 hours.
If one of the batteries in a system fails and is not replaced, it prevents the other battery from completing a maintenance discharge. Not only does this condition reduce the lifetime of the remaining battery, but it also prevents a maintenance discharge cycle from occurring after the battery has provided protection for at least 2 critical saves or 10 brown outs. Preventing this maintenance cycle from occurring increases the risk that the system accumulates a sufficient number of power outages to cause the remaining battery to be discounted when calculating whether there is sufficient charge to protect the system. This condition results in the system entering service state while the one remaining battery completes a maintenance discharge. I/O operations are not permitted during this process. This activity takes approximately 10 hours.