Apologies for the naïve question, but I spent some time Googling and reading and didn't find a clear answer to this.
We have a data set that gets fetched from the network and changes occasionally. I'd like to untie this update from normal operation-that is, on the off-chance that the network is down at the precise instant that we check for the data set, I'd like things to continue operating. So I'm thinking that if we cache a copy of the data set on disk (the contents aren't sensitive), we could try to fetch; if we can't fetch, we shrug and continue; if we can, we compare the data read with the existing data (there's a timestamp) and only rewrite if it's changed. But the data is also shared across tasks, so we don't want a window where it's half-written and some task tries to read it. A GDG seems like it would work great for this: the number of generations could be defined as low as two, so the update would write the "other" copy, and the next time one of the tasks tries to read it, it would get the newer one. So here's my question (aside from the obvious one of "Am I missing something above that makes this dumb"): If a jobstep runs with a DD for a GDG that's got DISP=MOD, and the jobstep reads but never tries to write the file, does a new, zero-length GDG get created? I'm of course hoping the answer is "No". Thanks, -- ...phsiii ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
