If you’re familiar with FDISK, LPAR is simlliar where you can “divide” an iSeries into several partitions giving each its own system name, etc. Some uses for this are:
To separate your Production system into two LPARs, one for Production “live” data, the other for your Developers and “test” data.
Others have used it strictly for QA.
I’ve also seen shops use LPARs for DR. In the event of multiple disk crash, you can switch your users to the other LPAR. Of course if your entire ISeries goes down, you’re out of luck with DR!
more at goggle: as/400 lpar