(Originally posted 2005-05-03.)
My thanks to Greg Dyck for pointing out the following on IBM-MAIN:
“The Store-CPU-Identifier now allows for a 8 bit partition identifier but the ESCON I/O protocols only allow for a 4 bit identifier. This is the reason that multiple channel subsystems must be implemented if you want more than 15 partitions on a CEC. FICON does not have this limitation.”
And to think ESCON’s only 15 years old. 🙂 I remember at the time having the EMIF support explained to me – including the LPAR number field. At the time 15 LPARs seemed an awfully large number, particularly as people were still grappling with how to configure machines with 2 or 3 LPARs for performance.