Mainframe, MVS and zOS Discussion

Hi,

What is the difference between MVS/XA and MVS/ESA in mainframes? Can they both be available on a single mainframe?

MVS/XA was the first 31-bit MVS operating system. It was later replaced by MVS/ESA in 1988, then by OS/390 in 1995. While either should run in an LPAR on a mainframe, I have not verified this myself. Furthermore, it would be unlikely to have them both running on a single machine since neither has been supported for many years.

Thanks Robert.

So they are basically based upon the same architecture and MVS/ESA is a successor of MVS/XA?

The basic architecture of IBM mainframes dates back to 1964 and the System/360. While this architecture has been extended considerably since then, programs that ran on a 360/30 machine under OS/360 or DOS/360 back then can still be run today on a zEnterprise machine running z/OS. MVS/XA extended the 24-bit addressing to 31-bit addressing; z/OS later extended this (again) to 64-bit addressing. If you seriously want to know more about MVS/XA and MVS/ESA, you need to use Google (or your favorite search engine) and start reading. IBM has used many names for their operating systems over the years as features have been added; MVS/XA and MVS/ESA were merely two of them.

Thanks for the direction Robert. Mainframe's information is too wide...

Mainframe info is Very wide, but for most people the history is just that - history.

Handy for some trivia type questions, but currently not running in a productno environment.

One way to run both on the same computer is to run a VM host with multiple "guests".

dick scherrer wrote:One way to run both on the same computer is to run a VM host with multiple "guests".

I did not get you dick?

There is another manframe operating system called VM (Virtual Machine). If this is the host software, other "guest" host operating systems may be run on that same system, allowing multiple "mainframes" with different operating systems to run at the same time.

This is probably not something you will use unless it is part of your environment and then someone alreay supporting the environment will know your specifics.

Sorry to be so long - this forum does not always sent an e-amil.

dick scherrer wrote:Sorry to be so long - this forum does not always sent an e-amil.

Hi Dick,

You can set "Notify me upon replies by default" in Edit posting defaults and you will be automatically notified of the first unread reply to your posts in every topic.

Thanks Dick, understood it.