Sysplex
A group of mainframe systems joined together so they behave as one, sharing work and data so that no single failure stops the service.
Also written Parallel Sysplex
A sysplex is a set of z/OS systems connected so they can share workload and data and be managed as a single unit. The full form, Parallel Sysplex, adds shared hardware that lets every system in the group read and write the same data at the same time, safely.
The point of it is continuous availability. If one system in the sysplex needs to be taken down, for maintenance or because something failed, the others carry the work and customers notice nothing. Software upgrades can be rolled through one system at a time while the service stays up.
It also allows a service to grow sideways. Rather than replacing a machine with a bigger one, another system joins the sysplex and starts taking a share of the transactions.
You will most often meet the term in the context of availability targets. When an organisation says its core banking service has not had planned downtime in years, a sysplex is usually the reason.
Related terms
- LPARA logical partition: one physical mainframe carved into several independent virtual machines, each running its own operating system.
- MainframeA large, highly reliable computer built to run enormous volumes of transactions and batch work for an entire organisation at once.
- IBM ZIBM's current family of mainframe hardware, and the brand name you will see on most modern mainframe job adverts.
- Online transaction processingHandling many small pieces of work in real time while someone waits: a card payment, a balance check, a seat booking.