Hal, I must respectfully disagree with the idea that shared DASD using Reserve constitutes risk of any magnitude, and eventually will lead to deadly embraces.
I operated sites with two and three production LPARS and no GRS for over 12 years without any problems caused by reserve, and never a deadly embrace. This included IMS, CICS and DB2. The first " embrace" problem we ever had was after MIM was introduced and we had soft embrace between the IMS RECON and the - resolved by converting both reserves, not just one. In my site now we run 10-16 LPARS, all with shared DASD and no GRS or MIM. Most of the x-system access is catalog, TSO and DFSMShsm backup and migration (DFSMShsm runs on one LPAR only). No performance issues (except the ones I create on purpose), and no Deadly Embraces. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of > Hal Merritt > Sent: Friday, January 22, 2010 9:38 AM > To: [email protected] > Subject: Re: [IBM-MAIN] SHARING USER CATALOGS WITHOUT GRS > > Presumably, more than just the catalog is to be shared. > > Often, reserves are issued against more than just the catalog volume(s). This > can (and eventually will) lead to 'deadly embraces' which can bring your shop > down. (BTDT) > > Sharing any DASD (be it catalogs or whatever) without global coordination is > not something one does unless one knows exactly what they are doing. But, if > one does know what they are doing, then they wouldn't do that in the first > place :-) > > If RESERVE were a viable alternative, then a lot of us would be doing just > that. > > Basically, you have two choices: > > 1. Use GRS (or equivalent) > 2. Don't share DASD. > > The good news is that implementing GRS should not cost much (if anything). > > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of > Glen Gasior > Sent: Friday, January 22, 2010 10:43 AM > To: [email protected] > Subject: SHARING USER CATALOGS WITHOUT GRS > > * > I have a requirement to share a production USER CATALOG with a test (not > development) lpar. Both lpars are MONOPLEX. > * > There is no GRS and will not be. No aliases on the test lpar will be assigned > to > this production lpar USER CATALOG. > * > I want to be certain serialization of the catalog takes place. I assume this > will > be via reserves. I want to be certain serialization is taking place between > the > two lpars on the USER CATALOG. > * > Please tell me of what must be in place for this to occur, especially any > gotchas that would bypass serialization. > * > No new program products will be purchased. > * > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html > NOTICE: This electronic mail message and any files transmitted with it are > intended > exclusively for the individual or entity to which it is addressed. The > message, > together with any attachment, may contain confidential and/or privileged > information. > Any unauthorized review, use, printing, saving, copying, disclosure or > distribution > is strictly prohibited. If you have received this message in error, please > immediately advise the sender by reply email and delete all copies. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
