Shutting down a cluster

If you want to remove all input power to a cluster (for example, the machine room power must be shutdown for maintenance), we you should use the Shutdown Down Cluster operation prior to removing power. Note: If you do not shut down the cluster before turning off input power to the uninterruptible power supply units, the cluster completes an emergency shutdown, which is powered from the uninterruptible power supply battery. This method drains power from the uninterruptible power supply needlessly, and the restart of the cluster is delayed while the uninterruptible power supply charges.

When input power is restored to the uninterruptible power supply units, they start to recharge. However, the SAN Volume Controller do not permit any I/O activity to be performed to the virtual disks (VDisks) until the uninterruptible power supply is charged enough to enable all the data on the SAN Volume Controller nodes to be saved in the event of an unexpected power loss. This process might take as long as two hours. Therefore shutting down the cluster prior to removing input power to the uninterruptible power supply units prevents the battery power from being drained and makes it possible for I/O activity to resume as soon as input power is restored.