On 1/5/2018 3:52 AM, John Eells wrote:
Jesse 1 Robinson wrote:
We would like to be able to access >65535 device addresses (UCBs)
from a single LPAR via a single IODF. The need is for bringing a new
DASD subsystem online while retaining the old subsystem until all
volumes can be copied across. We currently have spare UCBs available,
but not enough to have all old and new devices online at the same
time. Is this possible?
You can have a maximum of 65,280* devices (not quite 64K) in
Subchannel Set 0. There are some things that can be accessed via
other SCSs, but IIRC the exceptions don't allow you to have more than
65,280 primary devices online concurrently. That includes all
devices, of course, including networking, tape, consoles, and such.
Skip, you might consider standardizing on larger capacity devices where
it makes sense to do so. We were *very* constrained on the total number
of UCBs we could have, based on architectural point-to-point (no switch)
FICON limits, and so we eliminated ALL of our mod-3 3390s a couple of
years ago. We now have only mod-9, mod-27 and mod-216 devices. (FWIW,
the most popular -- and most numerous -- ended up being the mod-27s.)
It's like a breath of fresh air!
--
Phoenix Software International
Edward E. Jaffe
831 Parkview Drive North
El Segundo, CA 90245
http://www.phoenixsoftware.com/
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