IBM 990 Reference Manual page 14

z990 Logical Channel SubSystems (LCSSs) and support for
greater than 15 Logical Partitions (LP)
In order to provide the increased channel connectivity
required to support the scalability of the z990, the z990
channel I/O SubSystem delivers a breakthrough in con-
nectivity, by providing up to 4 LCSS per CEC, each of
which can support up to 256 CHPIDs with exploitation soft-
ware installed. This support is provided in such a way that
is transparent to the programs operating in the logical par-
tition. Each Logical Channel SubSystem may have from 1
to 256 CHPIDs and may in turn be confi gured with 1 to 15
logical partitions. Each Logical Partition (LPAR) runs under
a single LCSS. As with previous 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.
Up tp 30 Logical Partitions
Up to 256 Up to 256
LCSS0 LCSS1
CHPIDs CHPIDs
Up to 256
Up to 256
LCSS2 LCSS3
CHPIDs CHPIDs
Physical Channel IDs (PCHIDs) SubSystem
In order to accommodate the new support for up to 1024
CHPIDs introduced with the Logical Channel SubSystem
(LCSS) a new Physical Channel ID (PCHID) is being intro-
duced. 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 pos-
sible to have LCSSs, there is still a single IOCDS to defi ne
the I/O subsystem. 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
ibm.com/servers/resourcelink.
IOCP - IOCDS
Partitions
LCSS0
CHPIDs
4F 12 52 EF
HCD - HSA or IOCDS - HSA
102 103 104 110
Physical Channels (PCHIDs)
Note: Crypto no longer requires a CHPID
14
Partitions
LCSS1
CHPIDs
00 02 12 2F EF
200 201 202 2B0 2C5
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