John, Thanks for the info. I know I need something like GPFS to do this. I'm NOT going to allow the programmer to just hope for the best and share the disk. What I was looking for was something akin to GPFS (hopefully without the admin overhead of HACMP) that would allow me to do this safely. GPFS is definitely an IBM product. Can you tell me what AFS is? NFS won't work for me because that is giving me a single point of failure in that if the NFS server goes down, I've lost access to the data from both sides of the AIX LPARs.
Rex -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of McKown, John Sent: Friday, June 15, 2007 12:55 PM To: IBM-MAIN@BAMA.UA.EDU Subject: Re: Quick AIX question rooted in a z/OS concept > -----Original Message----- > From: IBM Mainframe Discussion List > [mailto:[EMAIL PROTECTED] On Behalf Of Pommier, Rex R. > Sent: Friday, June 15, 2007 12:41 PM > To: IBM-MAIN@BAMA.UA.EDU > Subject: Quick AIX question rooted in a z/OS concept > > > Hi all. > > I know this isn't a z/OS question but I don't think any of us live in > a homogeneous environment and the best way I can think of asking this > AIX question is to word it in z/OS terminology. > > I have an application developer who wants to have 2 AIX LPARs access > shared disk. He thinks he can just have me point the LUN on the SAN > to both LPARs and everything will work just fine. On my "Z", I can > set up GRS or a third-party competitor to this to serialize I/O > requests from various LPARs/machines. Is there something in AIX that > performs a similar function? I asked this of an AIX list and the > response I got back was something called GPFS which they say can do > this. > Unfortunately it appears as though I would need to buy and activate > HACMP to use GPFS. Is there something else, more of a stand-alone > product like GRS that would allow me to share a disk LUN across > multiple AIX LPARs without having the LPARs step on each other? > > Thanks and have a happy Friday. > > Rex You simply CANNOT DO THIS!! If you actually tried, you'd end up scragging the UNIX filesystem. The only way to "share" data between UNIX systems is via something like NFS (or GPFS or AFS or some other type of thing). This applies even in z/OS UNIX. If you create an HFS or zFS filesystem and attempt to mount it on multiple z/OS systems which are not in the same Parallel Sysplex with the appropriate setup, then you will "fry" the UNIX filesystem. I've done it (by accident). Trying to share a UNIX filesystem would be like trying to share a single VSAM file in UPDATE mode between two different batch jobs on two different z/OS images, and you didn't have RLS. There are some UNIX filesystems (the aforementioned AFS or GPFS) which have something like RLS so that filesystem information can be shared between the two UNIX systems. UNIX buffers all the disk I/O into local caches. With two separate UNIX systems, you have two separate caches and no communications between them so that the caches remain coherent. Image trying to run a multitask system with shared memory, but no "locking" or other "safety precautions". You end up, eventually, with trash. Bottom line: Not possible except with the aforementioned filesystems such as AFS or GPFS. I am fairly sure the GPFS is an IBM filesystem for AIX systems. -- John McKown Senior Systems Programmer HealthMarkets Keeping the Promise of Affordable Coverage Administrative Services Group Information Technology The information contained in this e-mail message may be privileged and/or confidential. It is for intended addressee(s) only. If you are not the intended recipient, you are hereby notified that any disclosure, reproduction, distribution or other use of this communication is strictly prohibited and could, in certain circumstances, be a criminal offense. If you have received this e-mail in error, please notify the sender by reply and delete this message without copying or disclosing it. ---------------------------------------------------------------------- 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
