In 2013 the IBM zEC12 (zBC12) introduced the 10GbE RoCE Express feature. RoCE Express provides an RDMA capable network adapter providing access to RDMA over Converged Ethernet (RoCE). RoCE provides an optimized network interconnect for System z communications. Along with RoCE Express, z/OS provided a new RDMA based solution called Shared Memory Communications over RDMA (SMC-R). SMC-R is a sockets based solution providing transparent access to RoCE for TCP sockets applications over standard Ethernet.
The IBM System z13 introduces the capability to share (virtualize) the 10GbE RoCE Express feature among multiple (up to 31) LPARs (or z/VM guest virtual machines) using standardized PCIe virtualization (SR-IOV) technology.
When RoCE Express is exploited by z/OS with SMC-R, the combined solutions provide two key value points:
- Improved latency that can provide improved transaction rates for latency sensitive transactional based workloads, and
- Lower CPU cost for workloads that transfer larger payloads (i.e. analytics, streaming, FTP, big data, data replication, web services, etc.)
SMC-R does this while preserving the critical qualities of services (load balancing, security, isolation, reuse of IP topology, etc.) required by system z clusters in enterprise data center networks without requiring any application or middleware changes along with zero or minimal operational changes.
When customers enable SMC-R they should immediately experience the benefits, and longer term the benefits can be extended as they expand their exploitation of RDMA technology on System z.
With the IBM System z13 RoCE virtualization capability users can now share RoCE Express features which:
- Extends access to RoCE to additional workloads across multiple z/OS instances (LPARs) which will reduce the number of required physical RoCE features
- Expands (effectively doubles) the bandwidth of your RoCE Express features by enabling concurrent use of both 10GbE RoCE Express physical ports
Customers who have multiple CPCs in a single site (or an extended LAN among multiple sites) with z/OS centric workloads (e.g. SYSPLEX, DB2, WAS, CICS, MQ, IMS etc.) will be natural candidates for benefiting from RoCE Express and SMC-R.
So, if you understand the technology but you’re not sure you have an environment that might benefit from it, then we can offer you some help. If you would like some guidance and assistance with assessing how your specific application workloads might be applicable to SMC-R, or possibly assess the potential level of benefits that you might anticipate for your environment, a new tool called Shared Memory Communications Applicability Tool (SMCAT) has been created. SMCAT has been provided to assist our customers with this assessment process. SMCAT is now available via PTF for z/OS V1R3 (UI24872) and z/OS V2R1 (UI24762) customers. SMCAT does not require SMC-R or any special hardware. Instead SMCAT monitors your existing TCP/IP workloads and produces a summary report to help you understand how your workloads might be eligible for and benefit from SMC-R and RoCE Express.
If you have additional questions about SMC-R, RoCE Express, RoCE virtualization or using SMCAT then your next step is exploring the reference materials provided at:
If you are just getting started then the FAQ document might be a good first step. You can also reach out to the author (Jerry Stevens) of this blog at this email: email@example.com