"Notional" means theoretical, speculative, imaginary, conceptual. A few years ago 56664 bytes for the maximum usable block size of a single stored data block of a 3390 geometry SLED was notional because there were really several thousand more bytes on each real track for hardware and software overhead (home address, Record Zero, inter-field gaps, inter-record gaps, and index point). The number of tracks per 3390 cylinder was never notionally 16. There were always 15 tracks usable for holding user data on both SLEDs and RAIDs. Today it is still notionally 15, but may really be whatever an inventor wants to use, and the real track size may be significantly smaller or larger than 56664. It was always my understanding that "a half-track block" did not mean a blocksize equal to 1/2 of the maximum single block size, but rather the maximum block size at which two blocks could be stored on one track. Thus a half-track block on a 3390 might be only 27998 rather than 28332. Bill Fairchild
----- Original Message ----- From: "John Gilmore" <[email protected]> To: [email protected] Sent: Monday, August 11, 2014 5:06:09 PM Subject: Re: Extents more than One for load modules library My preceding post could have been worded more felicitously: one 3390 geometry had/has a notional track size of 56664 bytes and 16 tracks per cylinder. A half-track block for it is thus 28332 bytes in size, and this is certainly less than 32760. John Gilmore, Ashland, MA 01721 - USA ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
