IBM has announced the availability of Linux running natively on its S/390 mainframes, although general availability won't be until the autumn. SuSE and TurboLinux are acting as distributors and first call of support for potential users.
Linux can either takes advantage of the mainframe's logical partitions to run natively, or as a VM/ESA guest operating system on G3 390s and later. IBM added similar capabilities to its AS/400 earlier this year. An implementation of IBM's Java 2 will follow in June, says IBM, and Big Blue has promised to eventually port WebSphere and Tivoli hooks to the platform too.
It's not the first mainframe Unix: Amdahl's continues to update its venerable System V R4 port, UTS. But the two Linux ports - one inside, and one outside IBM - have progressed remarkably quickly.
Since System 390 doesn't even know about ASCII natively, let alone TCP/IP, this is all very clever, but who'd want to use it?
SuSE's HA architect Volker Weigand tells us that in addition to infrastructure uses such as running Apache or sendmail servers, he had customers waiting to evaluate it running SAP R/3. "It's just another platform for us that doesn't require special treatment" says Weigand.
As it stands, S/390 Linux is a few screws short of the full toolbox. It's not possible to failover between partitions - that requires some kind of heartbeat code and IP takeover. Nor as we understand it can you yet perform the kind of load balancing between partitions that you can do with say Red Hat's Piranha.
But on the other hand, that not might matter too much. There's plenty you can do natively on an S/390 that you can't do on a PC or even a lot of PCs. CPUs can be added or removed on the fly. And the System 390's I/O architecture allows you to connect to disks over IBMs fast fibre optic FIBON and ESCON interfaces to distances of up to 30 miles.
Princeton's Virtual Penguin Project is taking advantage of such features, so mainframe Linux will gradually spawn some unique features. Oh, and thanks to the BOCHS emulator it even runs Windows. ®