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azar.mhd

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PostPosted: Fri Feb 26, 2010 8:25 am
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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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enrico-sorichetti

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PostPosted: Fri Feb 26, 2010 9:59 pm
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You might want to take a look at
publibz.boulder.ibm.com/zoslib/pdf/zosbasic.pdf

or better at
ABC of ZOS system programming volume 10
www.redbooks.ibm.com/abstracts/sg246990.html

wher all You might want to know about lpar is explained very well
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Robert Sample

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PostPosted: Fri Feb 26, 2010 9:59 pm
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Yes, in fact you can assign separate IP addresses to each LPAR so that it can communicate as a stand alone machine to other machines. PC partitions are hard drive partitions, which are nothing like the virtual machine concept of an LPAR.
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aajakashif

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PostPosted: Fri Feb 26, 2010 11:31 pm
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Azhar, welcome to the Mainframe world.

You go thru this pdf and it will give you the basics about mainframe::

www.redbooks.ibm.com/Redbooks.nsf/RedbookAbstracts/sg246366.html
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MBabu

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PostPosted: Sat Feb 27, 2010 5:48 am
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The easiest way to think of this for me is to think of VMWARE ESXi (see vmware.com) where you have two completely different systems running on the same hardware and there is some magic piece that keeps them from clobbering each other. The same CPU/Disks/Memory and other things can be running z/OS, VM, and Linux at exactly the same time and neither one knows the other is there. They might be able to communicate, but they don't need to know that they share the same hardware. Some systems do know they share the same hardware and take advantage of that but that is much more advanced than what you are asking about.
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