(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. đŸ™‚ 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.

Published by Martin Packer

I'm a mainframe performance guy and have been for the past 35 years. But I play with lots of other technologies as well.

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