bi...@mainstar.com (Bill Fairchild) writes: > Lynn, > > I signed in to LinkedIn and was unable to find the reference, so > thanks for including the URL for the missing LinkedIn reference. I > read through that reference and saw 16 comments, only one of which > mentioned very bad throughput for CKD disks. No technical explanation > was given for the bad throughput; i.e., was it hardware limitations in > CKD, software limitations in Oracle, etc.? This comment was posted 23 > days ago, ca. 28 years after IBM first announced ECKD and > forward-thinking users began planning to junk their CKD by going to > ECKD.
re: http://www.garlic.com/~lynn/2011e.html#31 "Social Security Confronts IT Obsolescence" http://www.garlic.com/~lynn/2011e.html#35 junking CKD; was "Social Security Confronts IT Obsolescence" I'm still waiting for followup ... it says zVM, zLinux and Oracle ... so presumably it is relatively current hardware, processors, disks, software, etc. The reference is that bad performance was rectified moving off CKD to some flavor of FBA (presumably some recent flavor of ECKD, lots of users may qualify CKD/FBA ... but I can understand lots of current users not bothering to make the CKD/ECKD distinction; I can't imagine any existing "z" mainframe with "real" pre-ECKD disks) That don't mention it as an age or legacy issue ... the zVM & zLinux aren't that old. There always is some possibility that zVM, zLinux, and/or current Oracle never bothered to optimize their (e)ckd support as well as they have FBA. pure conjecture ... a possible motivation for not bothering with fine-tuning any (e)ckd support is that these days all (e)ckd devices are really some form of FBA device with an additional eckd simulation layer on top. Given native FBA device support ... going directly to the native FBA device eliminates an extraneous eckd simulation layer (aka for any eckd device, an equivalent native FBA device could be used w/o the additional, unnecessary eckd layer). the ckd/eckd simulation layer continues to live on because MVS (& its descendants) have been unable to support the native devices. misc. past posts mentioning fba, ckd, multi-track search, etc http://www.garlic.com/~lynn/submain.html#dasd -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- 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
