IBM Z10 EC manual Internal Battery Feature Recommendation

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 Inter- faces, 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 at 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 protection 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 time stamped 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.