[email protected] (Christopher Y. Blaicher) writes: > Your right, things are a little confusing. > SECTORS - Think of it as 224 pieces of pie. It is, I believe, physical. > CELL - Also physical, but I think of them as little chunks of data, > which may be your data or control data for the hardware. > TRACK BALANCE - How much room is left on the track if you were to > write a single block. Look up TRKBAL macro. > > That extra calculation is for device control information, part of > which I know is CRC, or at least that is what I was told. All that > stuff other than the COUNT-KEY-DATA areas are for the hardware and we > mortals can't see it, but it is there.
and all that is now archaic fiction since no real CKD have been made for decades, being simulated on industry standard fixed-block this is the "real" format ... giving both 512byte FBA and the newer 4096byte FBA https://en.wikipedia.org/wiki/Advanced_Format part of the change justification is 4096byte is more "efficient" ... 15byte "gap, sync, address mark" for each phsical record and "512" has 50byte ECC and 4096 has 100byte ECC for each record (eight 512 has 400byte ECC total) ... 512byte efficiency 88.7% and 4096byte efficiency 97.3% -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
