Restrictions associated with zEnterprise® servers
are:
- Functional limitations: Not all zEC12 or zBC12
functions are available in every z/OS release. See the following and
for a list of the zEC12 and zBC12 functions available in each z/OS
release.:
Some functions have migration or exploitation considerations
(see Actions you can take before you order a zEC12 or zBC12 server and Migration and exploitation considerations for zEC12 and zBC12 server functions.
) Many functions are enabled or disabled, based on the presence or
absence of the required hardware and software. If you wish to position
yourself to exploit any new zEC12 or zBC12 functions, you can install
the software and hardware in either order; that is, there is no requirement
to install either software or hardware first to exploit a specific
function. However, because of outage windows and testing considerations,
you might want to consider installing all the required software first,
then upgrading the hardware and, finally, updating your customization
to exploit the new functions.
- zEC12 and zBC12 servers in a sysplex:
- A Parallel Sysplex® that contains an zEC12 or zBC12 server either for a z/OS® image or a CF image can only
contain other zEC12 or zBC12 servers or zEnterprise z196, z114, z10™ EC, or z10 BC
servers.
If you are running z/OS on
any servers earlier than a z10 EC
or z10 BC server, you cannot
add a zEC12 or zBC12 server to that sysplex; that is, you will not
be able to perform rolling IPLs to introduce a zEC12 or zBC12 server
if you have any of the earlier servers either as z/OS images or coupling facility images in the
sysplex.
The earlier servers in the sysplex must be upgraded
to System z10 or later to have
zEC12 or zBC12 servers supported in the sysplex. If you have any z/OS images or coupling facility
images on an earlier server, and you intend to introduce a zEC12 or
zBC12 server into that sysplex, you must migrate those images to a
System z10 (or later) server
before introducing the zEC12 or zBC12 server.
If you are currently
using ESCON CTCs for GRS ring
configurations within a sysplex, consider using XCF signalling in
a GRS ring configuration. XCF sysplex signalling is preferred instead
of GRS CTC connections. Note that ESCON CTCs
are not supported on a zEC12 or zBC12 server and if you choose not
to convert to XCF signalling, you will have to install toleration
maintenance to enable GRS to use FICON® for
GRS ring configurations. This support does not enhance the robustness
of GRS-managed CTCs and the toleration must be installed across GRS
complex. See Migrate to GRS-managed FICON CTCs.
- The Integrated Cluster Bus 4 (ICB-4) Coupling Links are
not supported on a zEC12 or zBC12 CPC. Use 12x InfiniBand coupling
links, which are designed to replace Integrated Cluster Bus 4 (ICB-4),
and to complement 1x InfiniBand and ISC-3 on a zEC12 or zBC12 server.
InfiniBand coupling can provide significantly improved service times
compared to ISC-3s for distances up to 150 meters. You can read about
InfiniBand coupling links in IBM® System z® Connectivity Handbook (SG24-5444).
- The zEC12 or zBC12 server cannot be connected to a Sysplex Timer (9037-002). The Server Time Protocol (STP) feature is
the follow-on to the Sysplex Timer. STP is designed
to allow multiple servers and coupling facilities to maintain time synchronization with each other
without requiring a Sysplex Timer. STP is a hardware
feature of the zEC12, zBC12, z196, z114, z10 EC, and z10 BC. To implement STP, see the STP web site and the publications
and other resources listed there. The STP web site is at http://www.ibm.com/systems/z/advantages/pso/stp.html .
The STP design introduced a
concept called Coordinated Timing Network (CTN). A CTN is a collection of servers and coupling
facilities that are time-synchronized to a time value called Coordinated Server Time. A CTN can be
configured in two ways:
- STP-only CTN, which does not require a Sysplex
Timer.
- Mixed-CTN (External Time Reference and STP), which does require a Sysplex Timer.
The Sysplex Timer provides the timekeeping information in a Mixed-CTN. Even though the zEC12 or
zBC12 servers do not support attachment to a Sysplex
Timer, they can participate in a Mixed-CTN that has a z10
server synchronized to the Sysplex Timer. This
maintains the capability for enterprises to concurrently migrate from an existing External Time
Reference (ETR) to a Mixed-CTN and from a Mixed-CTN to an STP-only CTN.
Note: The zEC12 and zBC12 will be the last high-end servers to support connections to an STP
Mixed-CTN. All servers in the network must be configured in STP-only mode. Consider migrating your
servers that require time synchronization, such as to support a base or Parallel Sysplex(R), to the
Server Time Protocol (STP).
- For a list of functions on the zEC12 or zBC12 server
that are planned to be discontinued on future servers, see Accommodate functions for the zEC12 and zBC12 servers to be discontinued on future servers
- Unsupported hardware features: The following hardware
features cannot be ordered and cannot be carried forward from
an upgrade on an earlier server to the zEC12 or zBC12 server.
- Power® Sequence Controller
(PSC).
- FICON Express®. You should begin migrating to FICON Express8S channels.
- FICON Express2. You should
begin migrating to FICON Express8S
channels.
- FICON Express4 4KM LX.
You should begin migrating to FICON Express8S
channels.
- OSA Express2. You should begin migrating to OSA-Express4S (GbE
LX and SX, 1000BASE-T, 10 GbE LR and SR).
- ESCON. You should begin
migrating to FICON Express8S
channels.
- Dial up modems. The currently available Network Time Protocol
(NTP) server option for ETS, as well as Internet time services available
using broadband connections, can be used to provide the same degree
of accuracy as dial-up time services. You should begin migrating from
dial-up modems to broadband for RSF connections
Carry forward hardware features: The following
hardware features are not orderable on zEC12 or zBC12 servers. If
they are installed on your existing server at the time of an upgrade
to a zEC12 or zBC12 server, they may be retained or carried forward.
- ISC-3. You should begin migrating from ISC-3 features (#0217,
#0218, #0219) to 12x InfiniBand (#0163 - HCA2-O or #0171- HCA3-O fanout)
or 1x InfiniBand (#0168 - HCA2-O LR or #0170 - HCA3-O LR fanout) coupling
links.
- FICON Express4 10KM LX.
You should begin migrating to FICON Express8S
channels.
- FICON Express4 SX. You
should begin migrating to FICON Express8S
channels
- Crypto Express3
Also, see Ensure you are running on supported servers and storage controllers