[Misteur-Z]

Last time I worked on mainframes in 2012 the price to have a legacy banking app running with around 300 transactions/sec on IMS or DB2 was just insane.

IMO any "modern" architecture can handle the load. After all Google, Apple, Facebook, Microsoft, Amazon, etc. are not running on mainframes (just taking mastodon examples).

The main difference between ARM, x86 or Power vs Z is that you can keep your CPU usage between 95-100% in production and not break everything.

[leokennis]

Yep. We migrated from IBM Z13 running COBOL + DB2 to HP machines hosting RHEL VM's running TIBCO, JAVA and Cassandra. Similar load as you mention.

Performance is really not an issue, especially when you factor in the price (we could easily double our servers and still be cheaper than a pretty baseline Z13).

Main pro of the mainframe is: you can basically not touch your code for decades and it'll still run fine, every technology on it and the hardware itself is rock solid.

Main pro of leaving the mainframe is: you don't need to worry as much about expensive/hard technical debt (i.e. EBCDIC text encoding, special hardware for everything), pricing/billing is much simpler and cheaper, way easier to switch technologies.

[anthk]

Mainframe have live CPU and RAM swapping. You can't even compare.

[bobbydreamer]

Yep. That's true