-----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Thompson, Steve Sent: Sunday, September 05, 2010 5:14 PM To: IBM-MAIN@bama.ua.edu Subject: JES2 vs. JES3
<SNIPPAGE> I have worked in both environments, and have migrated between the environments, and even started a VSE to MVS/JES3 project -- my specialty was ALC and operations (just before I was hired by Amdahl) with CTG. Going back to the '70s, I vaguely remember a rule of thumb (if you were building a shop or converting from non-IBM to IBM): If you are going to run up to 3 CPUs (basically a Box, or CEC as it would be called today) in a site, you would use JES2 because JES3 Global was expensive (in CPU cycles). If you were going to have 3 or more CECs in a site, you would give strong consideration to JES3. Today, I have been looking at features I was familiar with in JES3 and it appears to me that many of them have been moved to BCP (basic control program) to make SYSPLEX operations easier to do. A good example of this is the change in console support and command routing. >From my perspective, and this is just my opinion having NOT used JES3 under z/OS, the only thing that JES3 would buy "us" today is the JOB scheduler that JES3 had, and Job Set Up. JOB Setup is a foreign concept to anyone who has done JES2 only. And it causes heartburn for people having to provide a JOB stream to/for a JES3 environment. The idea that JES3 and MVS can both manage tape drives/mounts and JES3 requires the data sets to exist before the JOB starts (otherwise you get a JCL error -- UNLESS the data set is created in the JOB via JCL) is hard for some to get their hands around. I have done work for a US Gov't agency, that was running a single CEC with JES3 Global and no locals. As I understood it, they did this because they were dependent on the JES3 job management (job scheduler) system. But they could not otherwise justify JES3. And if they had not been a JES3 shop in years gone by, they would have just gotten a simple job scheduler. I would like to hear from current JES3 users and what they think. Regards, Steve Thompson ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
