Inter-record gaps between each physical block take space on the track away from data, not to mention count and key parts of each physical block (CKD means count-key-data).
There is actually not any physical reason for IRG between physical blocks any more since we no longer have physical 33x0 devices (they are all virtual), but the concept is still implemented in the DASD controllers for compatibility. Peter -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Oscar Sent: Monday, October 25, 2021 10:44 AM To: [email protected] Subject: VSAM: Why a CISIZE of 4KB has 12 phyrecs/Track, not 13? Hi there, There's something I'm being missing, but acording to my numbers, there should be 13, not 12: Bytes per track: 56,664 bytes Bytes accessible per track: 55,996 bytes CI size: 4096 Physical record size: 4096 bytes Physical records per track (Bytes accessible per track / physical record size): 55,996 / 4096 = 13.6708984375 = 13???? What I'm missing? Thanks! -- This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
