On Thu, 14 Sep 2006 18:29:19 -0400, Thompson, Steve (SCI TW) wrote: >-----Original Message----- >From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On >Behalf Of Tom Schmidt >Sent: Thursday, September 14, 2006 5:22 PM >To: IBM-MAIN@BAMA.UA.EDU >Subject: Re: IDCAMS and DF/SORT support for LBI > ><snip> >LBI is limited to tapes, not DASD. (Too bad - I would like to see the >3390 geometry disposed of at long last. 3390's track length is getting >cramped.) ><snip> > >The 3390 does not have a problem with LBI. IBM has a problem with DASD >and LBI. Something about the architecture of a DCB...
(Is it really the DCB that's the limit? I don't think so.) The tapes use DCBs (and only DCBs) and they managed to overcome the 32760 byte limitation inherent in the original question here. 3390 uses either DCBs or ACBs (a handy alternative, eh?) and the folks in San Jose have worked some serious magic recently to mine unused and then underused bytes, nybbles and bits out of the various I/O control blocks in order to provide the somewhat recent support for million-plus track files on DASD. All I'm asking is: since a 3390-54 is still anchored on 3390 geometry, isn't it time yet to expand that (virtual) track length to something vaguely similar to the underlying shark disks? Or, better yet, bring out a new DASD architecture. Maybe FBA or maybe (by now) something better. -- Tom Schmidt Madison, WI (Every few years I dust off the old gripes... sooner or later maybe...) ---------------------------------------------------------------------- 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
