490 IBM z13s Technical Guide
D.3.1 Internal Shared Memory technology overview
ISM is a new function supported by the z13 and z13s machines. It is the firmware that
provides the connectivity for shared memory access between multiple operating systems
within the same CPC. It provides the same functionality as SMC-R but without physical
adapters like the RoCE card, using instead virtual ISM devices as SMC-R. It is a Hipersocket
like function that provides guest-to-guest communications within the same machine.
Figure D-11 shows a possible solution using SMC-D only.
Figure D-11 Connecting two LPARs on the same CPC using SMC-D
Both SMC-D and SMC-R technologies can be used at the same time on the same CPCs.
Figure D-12 shows a fully configured three-tier solution using both SMC-D and SMC-R.
Figure D-12 Clustered systems: Multitier application solution. RDMA, and DMA
D.3.2 SMC-D over Internal Shared Memory
ISM is a virtual channel similar to IQD for HiperSockets. A virtual adapter is created in each
OS. Using the SMC protocol, the memory is logically shared. The network is firmware
provided. A new device is required to manage that virtual function. SMC is based on a TCP/IP
connection and preserves the entire network infrastructure.
SMC-D is a protocol that allows TCP socket applications to transparently use ISM.
IBM z13
z/OS z/OSLP 1 LP 2
DB2
ISM
VCHID
DRDA
System z vPCI Firmware
Shared Memory Communications
vPCI ISM Virtual Functio nvPCI ISM Virtual Functio n
Sockets SMC SMC Sockets
CICS
Shared Mem Shared Mem
FID 1
FID 2
SMC-R and SMC-D enabled platform
z/OS image 1 (WAS)
z/OS image 3 (WAS)
Shared Memory Communications
via DMA (SMC-D using vPCI ISM)
client
Shared Memory Communications
via RDMA (SMC-R using RoCE)
SMC
RDMA enabled (RoCE)
Clustered Systems: Example: Local and Remote access to DB2 from WAS (JDBC using DRDA)
SMC-R enabled platform
shared memory
Sockets
SMC
Server
shared memory
Sockets
z/OS image 2 (DB2)
shared memory
client
Sockets
SMC
RoCE
RoCEISM ISMVCHID
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