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z890 Logical Channel SubSystems (LCSSs) and support for
Greater than 15 Logical Partitions (LPARs)
The z890 I/O subsystem is a breakthrough in connectivity
by providing up to 2 LCSS per server, and each LCSS can
support up to 256 CHPIDs when exploitation software is
installed. As the z890 is a single I/O cage confi guration it
will support up to a maximum of 512 CHPIDs of which up
to 420 CHPIDs can be ESCON channels. This support is
provided in such a way that is transparent to the programs
operating in the Logical Partition (LP). Each Logical Chan-
nel SubSystem may have from 1 to 256 CHPIDs and may
in turn be confi gured with 1 to 15 Logical Partitions. Each
Logical Partition runs under a single LCSS. As with previ-
ous zSeries servers, Multiple Image Facility (MIF) channel
sharing as well as all other channel subsystem features
are available to each Logical Partition confi gured to each
Logical Channel SubSystem. The z890 supports up to 30
Logical Partitions. (Note: The lowest Capacity Setting 110
can support up to 240 CHPIDs and up to a maximum of 15
LPARs.)
Physical Channel IDs (PCHIDs) SubSystem
In order to accommodate the support for up to a maximum
of 512 CHPIDs on z890 with the Logical Channel SubSys-
tem (LCSS) a new Physical Channel ID (PCHID) is avail-
able. The PCHID represents the physical location of an I/O
feature in the I/O cage. CHPID numbers are no longer pre-
assigned and it is now a customer responsibility to do this
assignment via IOCP/HCD. CHPID assignment is done by
associating a CHPID number with a physical location, the
PCHID. It is important to note that although it is possible
to have 2 LCSSs, there is still a single IOCDS to defi ne the
I/O subsystem, each LCSS can support CHPID 00-FF, and
the CHPID must be unique within the LCSS. There is a new
CHPID mapping tool available to aid in the mapping of
CHPIDs to PCHIDs. The CHPID Mapping tool is available
from Resource Link at: ibm.com/servers/resourcelink.
Logical Channel SubSystem (LCSS) Spanning
The concept of spanning channels provides the ability for
a channel to be confi gured to multiple Logical Channel
SubSystems and therefore they may be transparently
shared by any/all of the logical partitions in those LCSSs.
Up to 30 Logical Partitions
Up to 256
CHPIDs
Up to 256
CHPIDs
LCSS0 LCSS1
Note: Crypto no longer requires a CHPID
Physical Channels (PCHIDs)
102 103 104 110 200 201 202 2B0 2C5
Partitions
LCSS0 LCSS1
12 52 EF4F 12 2F EF00 02
IOCP - IOCDS
Partitions
CHPIDs CHPIDs
HCD - HSA or IOCDS - HSA