I'm not sure which poster said..
" Blind pursuit of backward compatibility has left us stuck with CKD even while most of the major logical methods of storage are FBA (VSAM, DB2, and PDSE)."
..but "blind" is completely out of court here and cannot go unchallenged in this forum. If CKD compatability had been abandoned then I've no doubt that it would have broken thousands of applications and would have been regarded by the customer base as a total show-stopper when considering an upgrade to any version of "MVS" or "S/390" or "z/OS" without CKD support.
Continuing to support CKD alongside new FBA-style access methods is, in my opinion, the way to go.
The conventional "CKD interpretation of an 8-byte disk address as MMBBCCCCHHRR shouldn't prevent other interpretations being mapped over it as part of the implementation of other access methods, and the simplest is that of a 64-bit byte offset into a "FBA-style" file. Plenty of life in the old iron's I/O dog yet!
As always, let's hear the business cases before we call for changes. Regards to all, Graeme. At 06:29 AM 3/07/2008, you wrote:
-----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Clark Morris Sent: Wednesday, July 02, 2008 2:39 PM To: [email protected] Subject: Re: Another difference between platforms... <snip> Blind pursuit of backward compatibility has left us stuck with CKD even while most of the major logical methods of storage are FBA (VSAM, DB2, and PDSE). <SNIP> Is it CKD vs. FBA? Or is this caused by it being cheaper to emulate CKD on RAID? And then, to continue with 3390 based geometry because it is cheaper to do that than to put out a new DASD device? IF FBA were such a wonderful thing, why hasn't some company that makes disk units (or did) put out FBA for "MVS" with their own device handler/driver? I'm just asking, because some of this was bandied about in the late '80s and into the '90s. Regards, Steve Thompson -- All opinions expressed by me are my own and may not necessarily reflect those of my employer. -- ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
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