<snip> We had a problem with a system with not enough page space defined. I remember discussions a long time ago on IBM-Main saying that if you have local page datasets of differing sizes, that you will never use all of the space on the larger page datasets if you add a larger page dataset. Is that still true? We have 3 locals and the PLPA and Common all allocated on the same 3390 Mod 3 pack. We just added a 4th page dataset that is a whole 3390 volume. Obviously, slightly larger than all the other locals.
We actually had to IPL the system, as one of the locals went over 80% full, and the system wouldn't allow address space create. Since we IPL'd with the same 3 page datasets, one of the locals is already at 59% full. We page added the 4th dataset after the system was up, and it is still at 0%. </snip> Generally, ASM will utilize the page datasets equally, so if they differ in size, the smaller one's will have a higher percent utilization. It sounds like you only had one local at the time. When it reached the 80% threshold, address space creation was stopped. The smallest local PAGEDS is the "control". The fact that the 4th dataset is at 0% indicated the pages on aux storage are from long term tasks (e.g. dfHSM). Where the task is up for days/months at a time. Usually, this has been the SMF30 records being retained for eventual write to SMF. It also indicates that there is not much pressure on real storage. All of that being said, my recommendation would be to have at least 2 locals of "nearly equal size". The first local would be specified in IEASYSxx and the second would be included via a PAGEADD in COMMNDxx. This will occur early enough in the IPL that both locals will be used equally. The local PAGEds's should be sized so that the max slot utilization does not exceed 30% on any individual dataset. This defeat the "block paging" algorithm and reduces the efficiency of ASM. HTH, ---------------------------------------------------------------------- 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
