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About Multiple operating systems.
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azar.mhd

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PostPosted: Fri Feb 26, 2010 8:25 am    Post subject: About Multiple operating systems.
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Hi all,

I heard that mainframe system can have different operating systems in different LPARS.
So please any one can give me a detailed information on this.

Thanks in advance
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Robert Sample

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PostPosted: Fri Feb 26, 2010 9:13 am    Post subject:
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That pretty much summarizes it -- an LPAR can run z/OS, z/VM, Linux and so forth. Each LPAR on a machine can run a different operating system depending upon system requirements.

What kind of detailed information do you think you need? Have you looked at the IBM web site? What other research have you done?
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azar.mhd

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PostPosted: Fri Feb 26, 2010 9:34 am    Post subject: Reply to: About Multiple operating systems.
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I am in an undergo training pro gramme on IBM mainframes.
My trainer said that mainframe can have multiple operating system on different LPARS. Can you suggest me any notes on this such as LPARS and O/s.

Still am in confusion about what exactly a LPAR. I know it is part of DASD. But i wanna know weather each LPAR is treated as a individual system or what ?

According to my knowledge In our institute we are accessing os/390. I think this will be the main o/s for our mainframe system. Then what exactly mean by multiple os. Is this means os on terminals ? Like we are using linux to access the mainframe on our terminals using 3270.

Please give me any link to that.
Thank you very much.
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dick scherrer

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PostPosted: Fri Feb 26, 2010 9:48 am    Post subject:
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Hello,

Your level of understanding is such that we cannot go into any depth.

An lpar is not "part of dasd". Logically, you can think of an lpar as an entire computer. One hardware box might support several logical computers, each managing their own resources (such as memory, dasd, tapes, printers and so forth).

Quote:
Then what exactly mean by multiple os.

Each of these logical computers might run the same or a different operating system.

Quote:
Is this means os on terminals ?
No.

Quote:
Like we are using linux to access the mainframe on our terminals using 3270.
Regardless of the pc operating system (linux, Windows, Ubuntu, etc), you are probably using some kind of 3270 emulator software to access the mainframe as the 3270 is the most common terminal used for connecting to an IBM mainframe.

Suggest you ask the trainer for information relative to where the class is technically.
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azar.mhd

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PostPosted: Fri Feb 26, 2010 9:53 am    Post subject:
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Thank you very much
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dick scherrer

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PostPosted: Fri Feb 26, 2010 10:14 am    Post subject: Reply to: About Multiple operating systems.
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You're welcome - good luck icon_smile.gif

d
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Anuj Dhawan

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PostPosted: Fri Feb 26, 2010 3:10 pm    Post subject:
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Quote:
what exactly a LPAR. I know it is part of DASD. But i wanna know weather each LPAR is treated as a individual system or what ?
No - it's not a part of DASD and 'am not very sure of the meaning of the sentence alos - what do you mean by that?

LPARs - Logical partitions are, in practice, equivalent to separate mainframes. Each LPAR runs its own operating system. This can be any mainframe operating system; (probably this is what your trainer meant). There is no need to run z/OS, for example, in each LPAR. The system programmers/planners may choose to share I/O devices across several LPARs, but this is a local decision. The system administrator can assign one or more system processors for the exclusive use of an LPAR. Alternately, the administrator can allow all processors to be used on some or all LPARs.
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Robert Sample

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PostPosted: Fri Feb 26, 2010 5:54 pm    Post subject:
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Quote:
According to my knowledge In our institute we are accessing os/390. I think this will be the main o/s for our mainframe system. Then what exactly mean by multiple os. Is this means os on terminals ? Like we are using linux to access the mainframe on our terminals using 3270.
OS/390 is an older operating system -- z/OS has been the current operating system for IBM mainframes for almost ten years now.

An IBM mainframe can be logically partitioned into multiple virtual machines -- each called an LPAR (Logical PARtition) -- and each virtual machine requires an operating system to run. There is no requirement for every LPAR to run the same operating system, and most sites use one LPAR to test new operating system releases (and often application changes) before placing them on the production system.

Terminals don't have operating systems. They may have some processing capacity but not much -- mainframe terminals can be considered extremely thin clients. A PC running a terminal emulator has an operating system, of course, but the terminal emulator itself is not an operating system. If you're using Linux on the PC to access the mainframe, then Linux is your local machine operating system.
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azar.mhd

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PostPosted: Fri Feb 26, 2010 8:36 pm    Post subject: Reply to: About Multiple operating systems.
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Quote:
An IBM mainframe can be logically partitioned into multiple virtual machines -- each called an LPAR (Logical PARtition) -- and each virtual machine requires an operating system to run


Then each LPAR will have one o/s that may or may not same with other. Can LPAR contain os other than z/os.

Where this z/os will exists in mainframe machine.

thanks.
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Anuj Dhawan

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PostPosted: Fri Feb 26, 2010 8:45 pm    Post subject: Re: Reply to: About Multiple operating systems.
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azar.mhd wrote:
Then each LPAR will have one o/s that may or may not same with other. Can LPAR contain os other than z/os.
Each LPAR runs its own operating system. This can be any mainframe operating system. There is no need to run z/OS, for example, in each LPAR - may be other LPAR has OS/390 (one good reason to have such a set-up is - because bean counters wanted that..icon_smile.gif)
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Robert Sample

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PostPosted: Fri Feb 26, 2010 8:49 pm    Post subject:
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Quote:
Can LPAR contain os other than z/os.
As you have already been told, an LPAR can run operating systems such as z/OS, OS/390, z/VM, z/TPF for example.
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azar.mhd

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PostPosted: Fri Feb 26, 2010 8:51 pm    Post subject:
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ok thank you very much. Now i am very clear about that.

Thanks again
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Anuj Dhawan

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PostPosted: Fri Feb 26, 2010 8:58 pm    Post subject:
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Robert - however, I'd like to know what a System Progrmmer has to say on such a question
Quote:
Where this z/os will exists in mainframe machine.
- I compiled the answer 3-4 times for this and then gave up...was not sure;... Nucleus fits as an answer?
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Robert Sample

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PostPosted: Fri Feb 26, 2010 9:10 pm    Post subject:
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The operating system exists in multiple spots. There's a copy on the load disk (which is the disk drive from which the load starts), but it is not an active copy -- more a potential copy. The active operating system sits in memory -- for each address space in the system, there is some of it in low memory and a lot of it in high memory just below the 16 megabyte line, and more of it above the line. Each address space has a copy of parts of the operating system, and there is an address space used pretty much exclusively by the o/s as well. So the best answer is that it is scattered around the system. How scattered depends upon where you draw the line -- nucleus certainly, but what about the link list? lpa? jes? which storage subpools? Patches applied via SMP/E? It can be a complicated question if you really want to give an accurate and complete answer!
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azar.mhd

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PostPosted: Fri Feb 26, 2010 9:14 pm    Post subject:
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Actually am very new to mainframe. Thats why i am comparing my normal system to mainframe thinking that hard disk is similar to dasd and LPAR with partitions.

Please dont mind.
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Robert Sample

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PostPosted: Fri Feb 26, 2010 9:40 pm    Post subject:
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Don't think of an LPAR as a partition -- it is most closely correlated to a virtual machine in the Windows / Intel / Unix world. In fact, IBM was doing virtual machines many, many, many years before VMWare and its ilk came along for Windows / Intel / Unix servers.
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Anuj Dhawan

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PostPosted: Fri Feb 26, 2010 9:42 pm    Post subject:
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Thank you , Robert. That helps.

have a nice weekend, icon_smile.gif
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azar.mhd

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PostPosted: Fri Feb 26, 2010 9:44 pm    Post subject:
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THANK YOU ALL
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dick scherrer

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PostPosted: Fri Feb 26, 2010 9:46 pm    Post subject:
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Hello,

Quote:
Actually am very new to mainframe
As i've said before - we were all new once upon a time. . . icon_smile.gif

Quote:
i am comparing my normal system to mainframe
What do you consider to be a "normal system"?

Yes "hard disk" and "dasd" are pretty much interchangeable.

An LPAR is a "logical partition", but an LPAR is logically an entire computer.

Whether this is similar to your definition of "partition" would depend on what you mean by "partition".
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azar.mhd

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PostPosted: Fri Feb 26, 2010 9:52 pm    Post subject:
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Quote:
What do you consider to be a "normal system"?


It means a PC with partitions ( drives c,d,e etc )

yes of-course, in PC also partitions are logically divided into parts.

Quote:
an LPAR is logically an entire computer.


Each LPAR can act as a one computer.

Am i correct ?
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