I've been following this with interest and have had to think about page data set design from a different angle, which I'll come to towards the end of this contri.
The point about continguous slot allocation remains valid. There has been a change, which I don't think materially affects this, round about the 1.2 timeframe. Perhaps someone from Poughkeepsie can comment on what I've tended to think of as "more aggressive slot harvesting". But I don't think that makes much difference to the argument about utilisation. The second point is the "leave enough room to dump that large DB2/WAS address space" argument. Actually, a fortiori, I'd say "leave enough space to dump the whole of real storage". So that gives another "ROT" of "leave free page space of about 1.5x the amount of real storage you have". Note: Both the "25%" and the "1.5x" ROTs are trying to simplify probabilistic things (as always). So, you know in your shop what happens when you fail the ROT. In the former case paging performance tanks. In the latter it's a real bad news day when that 6GB DB2 subsystem dumps. (I've seen the latter happen and it's not pretty - when you don't have the paging space to contain it.) Also note: You don't really have to choose which of these two considerations. Go for both. Which takes me back to my current client - who's asked me for metrics to track. (I'd neglected to put the "25%" metric in, so thanks all for that.) Regards, Martin Martin Packer, MBCS CITP Martin Packer/UK/IBM 020-8832-5167 in the UK (+44) (MOBX 273643, Internal 7-325167, Mobile 07802-245584) "Las cosas de palacio van despacio" External Blog: http://www-128.ibm.com/developerworks/blogs/dw_blog.jspa?blog=476 Internal Blog: http://barney.adtech.internet.ibm.com/pilot/weblogs/comments/[EMAIL PROTECTED] ---------------------------------------------------------------------- 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
