Second level system disks allocated as an MDISK on real cylinders 1-end has a lot of advantages. Especially for experienced VM customers.
But it also keeps one from IPLing that sysres allocated as a MDISK (beginning on real cyl 1) on the bare metal when things go bump in the night. On that dark and stormy night one wants ANY type of VM system to be IPLable to permit rapid recovery of the production 1st level system (usually without backup tapes!). When that happens, that (540RES ?) sysres beginning on real cylinder zero sure does look nice when it IPLs from the HMC. Yes, we have an emergency 1-pack 3390-3 IPLable z/VM sysres DASD ... but how many newbies do? No IBM doc that I recall describes creating a 1-pack emergency IPL disk, nor the importance of creating it immediately after fully completing the first z/VM installation for the first time (when one is most likely to make an inexperienced choice, taking down that only z/VM system. So, as a wise, famous lil' ol' IBM VM'er often says: "It depends." Mike Walter Hewitt Associates The opinions expressed herein are mine alone, not my employer's. "David Boyes" <dbo...@sinenomine.net> Sent by: "The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU> 09/02/2009 07:36 PM Please respond to "The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU> To IBMVM@LISTSERV.UARK.EDU cc Subject Re: Download Vm Tape On 9/2/09 8:09 PM, "Alan Altmark" <alan_altm...@us.ibm.com> wrote: > Alas, my friend, it was your second level system on fullpack minis that > used the same volsers! You forgot to change one! The LPAR I/O config was > "in conformance to policy". I stopped using fullpack minidisks for 2nd level systems long, long ago. Hmph. But, your gun, your foot... > You always want to be able to say, "Your Honor, I took every reasonable > precaution. If I can direct your attention to line 12 of Exhibit B...." That's why I don't use real cylinder 0 for maintenance systems in the first place. The information contained in this e-mail and any accompanying documents may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient of this message, or if this message has been addressed to you in error, please immediately alert the sender by reply e-mail and then delete this message, including any attachments. Any dissemination, distribution or other use of the contents of this message by anyone other than the intended recipient is strictly prohibited. All messages sent to and from this e-mail address may be monitored as permitted by applicable law and regulations to ensure compliance with our internal policies and to protect our business. E-mails are not secure and cannot be guaranteed to be error free as they can be intercepted, amended, lost or destroyed, or contain viruses. You are deemed to have accepted these risks if you communicate with us by e-mail.
