On 11/23/2022 5:19 PM, Mike Schwab wrote:
Not sure when it changed (at least a decade ago), I think the mainframe reads and writes full tracks at a time anymore.
In a modern DASD subsystem, all operations are full track: read, write or replicate.
However, the mainframe itself (as defined by the IBM Z CPC running z/OS et al) does no such thing.
There are DASD I/O opcodes that allow you to read or write a track at a time (for example RTD and WTD), but the use of such opcodes is by no means the norm.
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