Parallel Sysplex® technology is an enabling technology, allowing highly reliable, redundant, and robust mainframe technologies to achieve near-continuous availability.

A properly configured Parallel Sysplex cluster is designed to remain available to its users and applications with minimal downtime, for example:

• Hardware and software components provide for concurrency to facilitate non-disruptive maintenance, like Capacity Upgrade on Demand, which allows processing or coupling capacity to be added one engine at a time without disruption to running workloads.
• DASD subsystems employ disk mirroring or RAID technologies to help protect against data loss, and exploit technologies to enable point-in-time backup, without the need to shut down applications.
• Networking technologies deliver functions such as VTAM® Generic Resources, Multi-Node Persistent Sessions, Virtual IP Addressing, and Sysplex Distributor to provide fault-tolerant network connections.
• I/O subsystems support multiple I/O paths and dynamic switching to prevent loss of data access and improved throughput.
• z/OS® software components allow new software releases to coexist with lower levels of those software components to facilitate rolling maintenance.
• Business applications are "data sharing-enabled" and cloned across servers to allow workload balancing to prevent loss of application availability in the event of an outage.
• Operational and recovery processes are fully automated and transparent to users, and reduce or eliminate the need for human intervention.