Kris, All true. I just didn't want to go into too much detail to express a simple point.
We do use DASD-vendor provided software (neatly avoiding posting the vendor name) which provides writes to all mainframe DASD to be concurrently written to DASD at both campuses. The DASD at each campus is then mirrored at each campus. In preparation for the D.R test, the DASD vendor breaks the software link, causing each campus to have their own set of up-to-date mirrored DASD. Following the test, the vendor restores the link, and the D.R. site DASD (now out of synch) is automatically refreshed from the production copy. I'm the z/VM guy, I won't pretend to know all the technical details about how all that magic is performed, but instead just get to enjoy its benefits. Yet I do sometimes miss those occasional 44-hour+ straight-through-without-sleep bits-and-bytes D.R. tests. That's when the creative problem-solving juices really flow - when something in the D.R. plan breaks and you need to quickly develop a creative solution. Now, with split campuses and "mirrored" (to use the simple term) DASD, it's mostly boring - even if we do get bragging rights every time because that z/VM system is back up within about 20 minutes of being given the LPAR. OTOH, z/OS with DB2 and a "few" more apps is "just slightly" more complicated. ;-) Mike Walter Hewitt Associates The opinions expressed herein are mine alone, not my employer's. "Kris Buelens" <kris.buel...@gmail.com> Sent by: "The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU> 12/16/2009 01:39 AM Please respond to "The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU> To IBMVM@LISTSERV.UARK.EDU cc Subject Re: VM Best Practices Mirroring does not replace good backup tapes: an accidental ERASE or FORMAT is mirrored perfectly well to your DR site. Secondly: if you simply have a two copy mirror, performing DR tests means you break the mirroring during the test and at that time you no longer have a mirror. 2009/12/16 Ivica Brodaric <ivica.broda...@gmail.com> Mike, I didn't mean to be smart, sorry if it came out that way. I just wanted to stress that everything you need to perform a DR, including hardcopy reports, utility tapes, DR procedure manual, CD's with software manuals, etc. has to be on a DR site or in the off-site storage, that's all. Of course, mirroring makes that much easier, because your DR system is just waiting to be IPLed. You have to send less stuff off-site, a lot of it can be kept on disks. Anything that you may need *before* you bring up VM, and that answers questions "where is...?" has to be either in the DR manual or in the hardcopy report on the DR site. My recent experience is also with mirroring - two sites running half of production load each, disk mirroring each way. LPAR configs were identical between sites and DR meant logging on one second level VM on each surviving VM(*) and PROFILE and other EXECs would take care of the rest. But I still miss the good ol' days of walking into a DR site and actually *doing something* to restore the system. Oh, wait, maybe I don't. It's just nostalgia. I was just much younger then. :-) Ivica (*) I don't suggest this setup unless you have plenty of storage and zero paging in production LPARs. At least that. -- Kris Buelens, IBM Belgium, VM customer support 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.
