Introducing long reach InﬁniBand coupling links

Now, Inﬁ niBand can be used for Parallel Sysplex coupling and STP communication at unrepeated distances up to

10 km (6.2 miles) and greater distances when attached to qualiﬁ ed optical networking solutions. Inﬁ niBand coupling links supporting extended distance is referred to as Long Reach 1x (one pair of ﬁ ber) Inﬁ niBand.

•Long Reach 1x Inﬁ niBand coupling links support single data rate (SDR) at 2.5 gigabits per second (Gbps) when connected to a DWDM capable of SDR (1x IB-SDR).

•Long Reach 1x Inﬁ niBand coupling links support double data rate (DDR) at 5 Gbps when connected to a DWDM capable of DDR (1x IB-DDR).

The link data rate will auto-negotiate from SDR to DDR depending upon the capability of the attached equipment.

Other advantages of Parallel Sysplex using Inﬁ niBand (PSIFB):

•Inﬁ niBand coupling links also provide the ability to deﬁ ne up to 16 CHPIDs on a single PSIFB port, allow- ing physical coupling links to be shared by multiple sysplexes. This also provides additional subchannels for Coupling Facility communication, improving scalability, and reducing contention in heavily utilized system con- ﬁ gurations. It also allows for one CHPID to be directed to one CF, and another CHPID directed to another CF on the same target server, using the same port.

•Like other coupling links, external Inﬁ niBand coupling links are also valid to pass time synchronization signals for Server Time Protocol (STP). Therefore the same coupling links can be used to exchange timekeeping information and Coupling Facility messages in a Parallel Sysplex environment.

•The IBM System z10 EC also takes advantage of

Inﬁ niBand as a higher-bandwidth replacement for the Self-Timed Interconnect (STI) I/O interface features found in prior System z servers.

The IBM System z10 EC will support up to 32 PSIFB links as compared to 16 PSIFB links on System z9 servers. For either z10 EC or z9, there must be less than or equal to a total of 32 PSIFBs and ICB-4 links.

Inﬁ niBand coupling links are CHPID type CIB.

Coupling Connectivity for Parallel Sysplex

You now have ﬁ ve coupling link options for communication in a Parallel Sysplex environment:

1.Internal Coupling Channels (ICs) can be used for internal communication between Coupling Facilities (CFs) deﬁ ned in LPARs and z/OS images on the same server.

2.Integrated Cluster Bus-4 (ICB-4) is for short distances. ICB-4 links use 10 meter (33 feet) copper cables, of which 3 meters (10 feet) is used for internal routing and strain relief. ICB-4 is used to connect z10 EC-to-z10 EC, z10 BC, z9 EC, z9 BC, z990, and z890. Note. If connect- ing to a z10 BC or a z9 BC with ICB-4, those servers cannot be installed with the nonraised ﬂ oor feature. Also, if the z10 BC is ordered with the nonraised ﬂ oor feature, ICB-4 cannot be ordered.

3.12x InﬁniBand coupling links (12x IB-SDR or 12x IB-DDR) offer an alternative to ISC-3 in the data center and facilitate coupling link consolidation. Physical links can be shared by multiple operating system images or Coupling Facility images on a single system. The 12x Inﬁ niBand links support distances up to 150 meters (492 feet) using industry-standard OM3 50 micron multimode ﬁ ber optic cables.

4.Long Reach 1x InﬁniBand coupling links (1x IB-SDR or 1x IB-DDR) are an alternative to ISC-3 and offer greater distances with support for point-to-point unre- peated distances up to 10 km (6.2 miles) using 9 micron single mode ﬁ ber optic cables. Greater distances can be supported with System z-qualiﬁ ed optical networking solutions. Long Reach 1x Inﬁ niBand coupling links sup- port the same sharing capabilities as the 12x Inﬁ niBand version, allowing one physical link to be shared by multiple operating system images or Coupling Facility images on a single system.