Steve (and others who have note used the IBMVM listserve web search capability),
:reminder on
Visit http://listserv.uark.edu/archives/ibmvm.html
It has a very powerful search capability to find answer to questions previously asked at IBMVM - before you even have to ask! :-)
:reminder off
I went to that site and into the search box entered: duplicate volsers
There were 17 hits going back to 98/10/13
A quick visual search of those 17 turned up:
---<snip>---
Date: Sun, 6 Nov 2005 14:29:59 -0500
Reply-To: VM/ESA and z/VM Discussions <VMESA-L@LISTSERV.UARK.EDU>
Sender: VM/ESA and z/VM Discussions <VMESA-L@LISTSERV.UARK.EDU>
From: Richard Corak <[EMAIL PROTECTED]>
Subject: Re: 2nd level install - duplicate volsers
In-Reply-To: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset="us-ascii"; format=flowed
At 01:00 AM 11/5/2005, you wrote:
>You can't always count on the lower address volsers being found
>first. That's the way it used to work before the XA/ESA I/O subsystem came
>into existence. I always thought that was still the case but John
>Franciscovich or one of the IBM Endicott VM gurus set the record straight a
>year or two ago on this list. Now, the order of what is found first is, at
>least to CP, random in that the interrupts that are returned aren't
>necessarily in ascending device number sequence.
>
>If you install this way onto duplicate volsers, you're only going to be
>safe if you set the test addresses offline at ipl in SYSTEM CONFIG and then
>when you bring up the test system, vary the addresses online and attach
>them to the guest. That would be the thing to do until you get the volids
>changed.
>
>Jim
No. Low device address wins, as long as the low address works.
This does not mean that it is OK to have duplicate volume labels.
From my explanation, first delivered here approx March 28, 2003,
and a few times since.
`Once again, here is how CP works at initialization regarding
`volume labels.
`
`* While RDEV blocks are allocated in subchannel number order,
` they are added to the SYSRIOIX radix tree by device number.
` See HCPIIDFS.
`* Many independent tasks are started, each initializing one device.
` These tasks are started in device number order, with no
` regard for subchannel number.
` See HCPIIO near label MOUNEXT.
`* It is unpredictable when initialization for any single device
` will be completed compared to any other.
`* For DASD that are to be attached to the system, whether CPOWNed
` or user volume, an ordered list is maintained in device number
` order. If multiple RDEVs are found to contain the same volume
` label, the RDEV for the higher device number is not added to
` the list. Effectively, only RDEVs with lower device numbers
` will be attached to the SYSTEM. See HCPIISDV. Message 0954.01
` is displayed at the operator's console for duplicates at higher
` device numbers.
`
`This algorithm was changed a number of times based on customer
`feedback. If you remember some sequence that doesn't match
`this, you're probably right: at many times in the past it didn't.
`
`But remember, if the device with the lower device number is
`somehow "wrong" (doesn't respond, I/O error, whatever), all
`your planning based on these initialization rules is probably
`broken. Keep unique volume labels for everything to be
`attached to SYSTEM.
`
`Advice about OFFLINE_AT_IPL is also good to remember.
Richard Corak
---<snip>---
Pay particular attention to the penultimate paragraph, which in my view pretty much states: when using duplicate volsers, you pay you money and take your chances.
Mike Walter
Hewitt Associates
The opinions expressed herein are mine alone, not my employer's.
| "Steve Gentry"
<[EMAIL PROTECTED]>
Sent by: "The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU> 06/29/2006 01:52 PM
|
|
If there are duplicate volume serial numbers and VM IPL's, does it use the first
volume it incounters? It seems to me that it does. I need to move my 520PAG volume.
Thanks,
Steve G
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