Given
A file pool consisting of
5 VDEV files on 5 separate real devices
2 cylinders per device
4096 block size
When:
a block chain is given Diag x'250' (async) for either read or write
such that 4 blocks are written to or read from each track within
the 5 files.
Question(s):
Does the 250 interface make any attempt to optimize I/O operations
by constructing chained channel programs for single-track or
consecutive-track multi-record writes/reads?
If that is not the case, is such optimization achieved at a more basic
level in z/VM real device I/O scheduling?
Curiosity killed the....
In either of the above cases (that is if channel programs are chained
based on intra-request I/O patterns), will either 250 or VM perform
inter-request channel program chaining for multiple async requests
targeting the same real device?
Thanks
--. .- .-. -.--
Gary Dennis
0 ...living between the zeroes... 0
