On Sat, 14 Aug 2010 10:24:02 +0100, Graham Harris <[email protected]> wrote:
>Is anyone actively using z10 (or z196!!) Large Pages in any significant way >yet? > Yes. On my clients WebSphere LPARs. First we used a small LFAREA and migrated some WAS regions to 64-bit. All was fine. Then on a weekend we allocated about 40G more to LFAREA and IPLed with the plan of converting more regions during the week. Much to our chagrin, Monday morning was a nightmare because paging went through the roof and thousands of enclaves were backed up in the system and couldn't be processed. It turns out the support didn't work as documented and 1M pages weren't really used for 4K when there was a shortage! After we opened a Sev 1 PMR with IBM during the problem IBM said something like "well, this isn't really supported". Huh?!!! This was z/OS 1.10 and I thought the support was z/OS 1.9 with PTFs. :-) The SHARE presentations I was at and documentation I had read sure made it sound like it was supported! During a tech call with IBM they admitted that the support wasn't working as intended (?) and the LFAREA was really just "stuck" there all for 1M pages and couldn't be used to back 4K page requests. So in essence we lost 40G of real memory when we IPLed. We converted a some additional regions to 64-bit over a few hours around lunch time to limp through the day without an outage, then backed out the changes that evening with an IPL along with any WAS regions that were converted to 64-bit. We are still using large pages but have been doing it in steps over the last 6 months (IPL with larger LFAREA, convert more WAS regions to 64-bit). We are z/OS 1.11 now and I honestly can't say if anything was changed in the code or if it works yet. The person closest to this works on the WebSphere team and I haven't asked. Maybe Elpida is lurking and can say. This weekend my client is doing a memory upgrade and also increasing LFAREA in one of the LPARs from around 64G to 80G (out of about 170G total). Mark -- Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS mailto:[email protected] Mark's MVS Utilities: http://home.flash.net/~mzelden/mvsutil.html Systems Programming expert at http://expertanswercenter.techtarget.com/ ---------------------------------------------------------------------- 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
