On Mon, 30 Jan 2012 22:35:02 +0000, Martin Packer <[email protected]> wrote:
> Because >of the virtualisation within modern disk controllers robustness favours >more, smaller. > What 6-9 3390-27 page volumes isn't robust enough? :-) And regardless of PAV and where the physical location is on the emulated DASD, if you put 5 smaller ones on _multiple_ mod-27s, isn't there more of a chance some of them end up on the same physical disk(s). One thing this thread didn't cover are some of the performance recommendations in the init and tuning guide related to large DASD. Recommendation #1, does say to only have one page data set per device. and in the z/OS 1.11 manual I have open it even has the updated bars on the left hand side. Writing to contiguous slots and over allocation is mentioned, but unless I missed it the "old" ROT (and health check) of not having more than 30% of the slots allocated is not specifically addressed. Certainly with 4K pages (for the most part) and 3390-27 (or bigger) that 30% ROT doesn't apply anymore? 50% of a mod-27 is still a helava lot of free slots. Mark -- Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS mailto:[email protected] Mark's MVS Utilities: http://www.mzelden.com/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: INFO IBM-MAIN
