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Application Programming Interface (API) to automate
STP CTN reconfi guration: The concept of “a pair and
a spare” has been around since the original Sysplex
Couple Data Sets (CDSs). If the primary CDS becomes
unavailable, the backup CDS would take over. Many sites
have had automation routines bring a new backup CDS
online to avoid a single point of failure. This idea is being
extended to STP. With this enhancement, if the PTS fails
and the BTS takes over as CTS, an API is now available
on the HMC so you can automate the reassignment of the
PTS, BTS, and Arbiter roles. This can improve availability
by avoiding a single point of failure after the BTS has taken
over as the CTS.
Prior to this enhancement, the PTS, BTS, and Arbiter roles
had to be reassigned manually using the System (Sysplex)
Time task on the HMC.
For additional details on the API, please refer to System z
Application Programming Interfaces, SB10-7030-11.
Additional information is available on the STP Web page:
http://www.ibm.com/systems/z/pso/stp.html.
The following Redbooks are available on the Redbooks
Web site: http://www.redbooks.ibm.com/.
• Server Time Protocol Planning Guide, SG24-7280
• Server Time Protocol Implementation Guide, SG24-7281
Internal Battery Feature Recommendation
Single data center
• CTN with 2 servers, install IBF on at least the PTS/CTS
– Also recommend IBF on BTS to provide recovery pro-
tection when BTS is the CTS
– CTN with 3 or more servers IBF not required for STP
recovery, if Arbiter confi gured
Two data centers
• CTN with 2 servers (one in each data center) install IBF
on at least the PTS/CTS
– Also recommend IBF on BTS to provide recovery pro-
tection when BTS is the CTS
• CTN with 3 or more servers, install IBF on at least the
PTS/CTS
– Also recommend IBF on BTS to provide recovery pro-
tection when BTS is the CTS
Message Time Ordering (Sysplex Timer Connectivity to Coupling
Facilities)
As processor and Coupling Facility link technologies have
improved, the requirement for time synchronization toler-
ance between systems in a Parallel Sysplex environment
has become ever more rigorous. In order to enable any
exchange of timestamped information between systems
in a sysplex involving the Coupling Facility to observe the
correct time ordering, time stamps are now included in
the message-transfer protocol between the systems and
the Coupling Facility. Therefore, when a Coupling Facility
is confi gured on any System z10 or System z9, the Cou-
pling Facility will require connectivity to the same 9037
Sysplex Timer or Server Time Protocol (STP) confi gured
Coordinated Timing Network (CTN) that the systems in its
Parallel Sysplex cluster are using for time synchroniza-
tion. If the ICF is on the same server as a member of its
Parallel Sysplex environment, no additional connectivity is
required, since the server already has connectivity to the
Sysplex Timer.
However, when an ICF is confi gured on any z10 which
does not host any systems in the same Parallel Sysplex
cluster, it is necessary to attach the server to the 9037
Sysplex Timer or implement STP.
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