The keeps its system software (firmware) in containers known as "Application Partitions". There are two application partitions, one of which is Active. When the system is operational, it is running off of the Active Partition, and the remaining (inactive) partition serves as a spare.

 

The Active partition cannot be upgraded while the system is running, so all upgrades are performed by replacing the Inactive Partition with the new firmware version.

When a software upgrade is performed, the spare partition is replaced by the upgrade. To use the firmware version just uploaded, you must activate the partition that it was uploaded to. You can either activate the partition immediately (also known as a One-Step Upgrade), or in a controlled manner during a scheduled service downtime (by Upgrading the Inactive Partition and manually Setting the Active Partition).

See also: Upgrading the SBC Communication Service Version
See also: Installing an ASM Package