Iocp - IBM z13s Technical Manual

Users of the Executing Fixed Channel Programs in Real Storage (EXCPVR) instruction can
construct channel programs that contain MIDAWs. However, doing so requires that they
construct an IOBE with the IOBEMIDA bit set. Users of the EXCP instruction cannot construct
channel programs that contain MIDAWs.
The MIDAW facility removes the 4 K boundary restrictions of IDAWs and reduces the number
of CCWs for EF data sets. Decreasing the number of CCWs helps to reduce the FICON
channel processor utilization. Media Manager and MIDAWs do not cause the bits to move any
faster across the FICON link. However, they reduce the number of frames and sequences that
flow across the link, so they use the channel resources more efficiently.
The MIDAW facility with FICON Express8S, operating at 8 Gbps, shows an improvement in
throughput for all reads on DB2 table scan tests with EF data sets compared to the use of
IDAWs with FICON Express2, operating at 2 Gbps.
The performance of a specific workload can vary according to the conditions and hardware
configuration of the environment. IBM laboratory tests found that DB2 gains significant
performance benefits by using the MIDAW facility in the following areas:
Table scans
Logging
Utilities
Use of DFSMS striping for DB2 data sets
Media Manager with the MIDAW facility can provide significant performance benefits when
used with applications that use EF data sets (such as DB2) or long chains of small blocks.
For more information about FICON and MIDAW, see the following resources:
The I/O Connectivity website contains material about FICON channel performance:
http://www.ibm.com/systems/z/connectivity/
DS8000 Performance Monitoring and Tuning, SG24-7146

7.12 IOCP

All z Systems servers require a description of their I/O configuration. This description is
stored in input/output configuration data set (IOCDS) files. The input/output configuration
program (IOCP) allows the creation of the IOCDS file from a source file that is known as the
input/output configuration source (IOCS)
z13s IOCP definitions: A new parameter for HiperSockets IOCP definitions on z13s
servers means that the z13s IOCP definitions need to be migrated to support the
HiperSockets definitions (CHPID type IQD).
On z13s servers, the CHPID statement of HiperSockets devices requires the keyword
VCHID. VCHID specifies the virtual channel identification number associated with the
channel path. Valid range is 7E0 - 7FF. VCHID is not valid on z Systems before z13s
servers.
IOCP required level for z13s servers: The required level of IOCP for z13s servers is V5
R1 L0 (IOCP 5.1.0) or later with PTFs. For more information, see the following manuals:
z Systems Stand-Alone Input/Output Configuration Program User's Guide, SB10-7166.
z Systems Input/Output Configuration Program User's Guide for ICP IOCP, SB10-7163.
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