STP CTN Merge in the zPET Environment
matthewbosko 110000BP5E Visits (553)
STP CTN merge is a new sysplex timing mechanism, enhancing availability, allowing two separate timing networks to be merged into one. Previously a disruptive action, the new functionality makes it now a concurrent action to sysplex(es) with in the CTNs.
STP CTN split or merge support was added with the IBM® z14™ family of servers and you can find more information about it in the IBM United States Hardware Announcement 118-75 [IBM
In our environment we have multiple parallel sysplexes and monoplexes that serve different purposes and are best suited to different phases of testing, such as sandbox & maintenance, test & development, and pre-production QA. The z/OS images are running V2R2 and V2R3 and span multiple CPCs which also includes a CPC that only has Coupling Facilities (a Stand Alone CF CPC). To achieve flexibility for testing with the right configurations, we share physical servers as much as possible so there are times we move servers from one CTN network (i.e., an STP CTN network split) to another (an STP network merge). This type of activity could warrant shutting down systems in a sysplex and take several hours of operational work to accomplish this planned outage. zPET was able to leverage this new functionality, splitting from and merging to STP networks dynamically, saving time without any planned or unplanned downtime.
We had two separate Coordinated Timing Networks (CTNs): zPET_STP and zPETSTP2. Both CTNs were connected to the same external NTP time source.
Here are some details of the unique CTNs:
zPET_STP CTN with M91 as the PTS/CTS:
zPETSTP2 with 1 CPC
Merging zPETSTP2 into the zPET_STP CTN:
While showing the zPETSTP2 CTN, I selected Join existing CTN from Advanced Actions:
I selected the existing zPET_STP CTN to join:
A confirmation panel appears, showing what the merged CTN will look like. Note the roles of the Merge to CTN are preserved and the merging CTN's roles don't persist.
I then selected APPLY to perform the merge:
Upon the CTN join task completing, the actual merge has started:
Now, when I look at the zPET_STP CTN, I see the zPETSTP2 CTN is joining and will complete soon:
The two CTNs have successfully joined the zPET_STP CTN:
zPET_STP after successful merge from zPETSTP2:
We were then able to IPL M191 z/OS images into the existing parallel sysplex in zPET_STP.