IBM z13s Technical Manual page 35

processing for z13s and z13 GA2 servers. It is intended to provide performance
improvements and better availability for critical business workloads that cannot afford any
impact to service levels. Flash Express is easy to configure, and provides rapid time to value.
Flash Express implements storage-class memory (SCM) through an internal NAND Flash
solid-state drive (SSD), in a PCIe card form factor. The Flash Express feature is designed to
allow each LPAR to be configured with its own SCM address space.
Flash Express is used in these situations:
By z/OS V1R13 (or later), for handling z/OS paging activity such as start of day
processing.
Coupling Facility Control Code (CFCC) Level 20 or later (CFCC Level 21 on z13s servers),
to use Flash Express as an overflow device for shared queue data. This configuration
provides emergency capacity to handle IBM WebSphere® MQ shared queue buildups
during abnormal situations, such as when "putters" are putting to the shared queue, but
"getters" are transiently not retrieving data from the shared queue.
Linux for z Systems (Red Hat Enterprise Linux (RHEL) and SUSE Enterprise Linux
(SLES)), for use as temporary storage.
Stand alone memory dumps and Supervisor Call (SAN Volume Controller) dumps.
Read/write cache, which greatly increases performance by allowing customer data to be
stored temporarily in a cache in the system's HSA RAM.
For more information, see Appendix H, "Flash Express" on page 529.
10GbE RoCE Express
The 10 Gigabit Ethernet (10GbE) RoCE Express is an optional feature that uses RDMA over
Converged Ethernet, and is designed to provide fast memory-to-memory communications
between two z Systems CPCs. It is transparent to applications.
Use of the 10GbE RoCE Express feature helps reduce CPU consumption for applications that
use the TCP/IP stack such as IBM WebSphere Application Server accessing a DB2 database
on z/OS). It can also help reduce network latency with memory-to-memory transfers using
SMC-R in z/OS V2R1 and later.
The 10GbE RoCE Express feature on z13s servers can now be shared among up to 31
LPARs running z/OS, and uses both ports on the feature. z/OS V2.1 with PTF or z/OS V2.2
supports the new sharing capability of the RoCE Express features on z13s processors. Also,
the z/OS Communications Server has been enhanced to support automatic selection
between TCP/IP and RoCE transport layer protocols based on traffic characteristics. The
10GbE RoCE Express feature is supported on z13, z13s, zEC12, and zBC12 servers, and is
installed in the PCIe I/O drawer. A maximum of 16 features can be installed. On zEC12 and
zBC12, only one port can be used, whereas on the z13 and z13s servers, both RoCE
Express ports can be used.
Shared Memory Communications - Direct Memory Access
In addition to supporting SMC-R, z13 servers support a new feature called Shared Memory
Communications - Direct Memory Access (SMC-D). Unlike SMC-R, SMC-D does not depend
on the RoCE Express feature. SMC-R affords low latency communications within a CEC by
using an RDMA connection.
IBM z Systems servers (z13 and z13s) now support a new ISM virtual PCIe (vPCIe) device to
enable optimized cross-LPAR TCP communications that use a new "sockets-based DMA", the
SMC-D. SMC-D maintains the socket-API transparency aspect of SMC-R so that applications
Chapter 1. Introducing IBM z13s servers
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