There is another consideration that makes allocating of Linux volume to a full-pack mini or letting it use cylinder zero very undesirable. If you regularly run FDR backups from MVS to dump the shared DASD volumes to tape, as part of your backup procedures, your backup will fail for full-pack Linux volumes. FDR chokes on the "corrupted VTOC" data that it sees in cylinder zero. There is a work-around for that problem that I don't think is worth dwelling on, but if someone needs that solution I'd be happy to post it.
Simon Kharnas Technical Support Consultant TIAA/CREF -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] Behalf Of Marcy Cortes Sent: Wednesday, March 17, 2004 2:38 PM To: [EMAIL PROTECTED] Subject: Re: Let Linux use Cyl 0? Well, technically VM only cares if the volumes are attached to SYSTEM (uservol include in SYSTEM CONFIG). If you use DEDICATE to assign them to Linux guests, then VM shouldn't much care, unless one of your Linuxes decides to label them something like 440W01 or something then watch out for fun at next IPL time. Not that I would ever do it that way - I didn't even give cyl 0 to MVS when we ran that as guests. I would think the only reason you'd want to do it is if you have to at times run in an LPAR without VM. Marcy Cortes Wells Fargo Services Co -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of Wolfe, Gordon W Sent: Wednesday, March 17, 2004 10:49 AM To: [EMAIL PROTECTED] Subject: Re: [LINUX-390] Let Linux use Cyl 0? I depends on how you've got it set up and what controls you have in place. If you're using VM as a hypervisor for Linux, VM has to be able to know what the volser of the DASD is. If your linux instances have root authority not controlled by you and they take it in mind to do a dasdfmt on a full-pack disk, including cylinder 0, and change the volser in doing so, then the next time VM is IPLed, that pack might not be found and the linux instance won't come up because the directory won't match the volser. "Nature and nature's laws lay hid in night: God said, 'Let Newton Be!' and all was light." - Alexander Pope "It did not last; the Devil howling 'Ho! Let Einstein Be!' restored the status quo." - John Collings Squire "God Rolled his dice, to Einstein's great dismay: 'Let Feynman Be!' and all was clear as day." - Jagdish Mehra Gordon W. Wolfe, Ph. D. VM Technical Services, The Boeing Company > ---------- > From: Steve Gentry > Reply To: Linux on 390 Port > Sent: Wednesday, March 17, 2004 10:13 AM > To: [EMAIL PROTECTED] > Subject: Re: Let Linux use Cyl 0? > > I do not think you should let anything other than VM itself use cyl 0. > As this is where VM keeps Vol id, disk map info, etc. $ALLOC$ is what > is some times called a place holder. The userid $ALLOC$ doesn't > actually do anything with it other than mark it or inform others that > this cylinder is occupied. I also set up a $EOV$ on each volume on > the last cylinder to help with keeping track of gaps that DISKMAP will > show. Steve Gentry > > > > > > "Davis, Larry" <[EMAIL PROTECTED]> > Sent by: Linux on 390 Port <[EMAIL PROTECTED]> 03/17/2004 11:50 > AM Please respond to Linux on 390 Port > > > To: [EMAIL PROTECTED] > cc: > Subject: Let Linux use Cyl 0? > > > Should I be letting Linux instances, under z/VM, utilize Cylinder 0? > Currently I allocate Cylinder 0 to $ALLOC$ and the rest of the volume > to the Linux image. > I CPFMTXA cylinder 0 in VM and give it a VOLSER. Then, I access the > devices > under Linux and dasdfmt them, and partition them using fdasd. > > Until I get FCP and an ESS setup to allocate larger volumes, I will be > using LVM for the larger file systems. I am planning to take full > volumes of 3390-3 DASD and create Logical volume groups from them. I > can split the devices between 4 FICON channels and 2 Controllers. > > Any recommendations? > > TIA, \|/ > (. .) > ____ooO-(_)-Ooo____ > Larry Davis, 6-2380 > > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, send > email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or > visit http://www.marist.edu/htbin/wlvindex?LINUX-390 > > > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, send > email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or > visit http://www.marist.edu/htbin/wlvindex?LINUX-390 > > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ************************************************************** This message, including any attachments, contains confidential information intended for a specific individual and purpose, and is protected by law. If you are not the intended recipient, please contact sender immediately by reply e-mail and destroy all copies. You are hereby notified that any disclosure, copying, or distribution of this message, or the taking of any action based on it, is strictly prohibited. TIAA-CREF ************************************************************** ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
