© 2013 IBM Corporation IBM Systems STP Save configuration across Power Outages for two server STP-only CTN July 13, 2009 Gregory Hutchison - May 10, 2012 update Gregory Hutchison - January 23, 2013 update

IBM Systems © 2013 IBM Corporation Page 2 Agenda  Prerequisites and set up required  Enablement of “Save configuration” function  CTN configuration rules after “Save configuration” function enabled  Rules for restoring roles (PTS/CTS, BTS) after the power is restored

IBM Systems © 2013 IBM Corporation Page 3 STP configuration and time information saved across power outages – two server CTN  Previously –If both servers experienced an unplanned power outage, user had to: Initialize the Time; Redefine the PTS, BTS, CTS roles  System Management Enhancement STP CTN configuration (PTS/CTS, BTS) can be configured so that –PTS/CTS, BTS roles possibly restored after a power outage –Initialize Time not required

IBM Systems © 2013 IBM Corporation Page 4 Prerequisites / required set up  MCLs required: –zEnterprise (zEC12, z114, z196) has this support integrated –z9 EC and BC Bundle 44 –z10 EC and BC Bundle 26 –Function not available on D55 (z990, z890)  If migrating from ETR network –PTS/CTS and BTS must first be assigned using procedures outlined in Server Time Protocol Implementation Guide, SG  If setting up a new STP-only CTN –PTS/CTS and BTS must first be assigned using procedures outlined in Server Time Protocol Implementation Guide, SG  STP-only CTN can only have two servers to enable this function –If more than two servers in operational CTN, Remove additional servers in the CTN by assigning them to a different to a different CTN, if possible Cannot proceed with this enhancement with more than two servers in CTN

IBM Systems © 2013 IBM Corporation Page 5 Enable “Save configuration” enhancement  Launch the System (Sysplex) Time task of the server that is the CTS –Go to the Network Configuration tab –Check the box “Only allow the server(s) specified above to be in the CTN” –Click Apply –“Only allow the server(s) specified above to be in the CTN” can be enabled only if two servers can communicate over coupling links Cannot select “Force Configuration” and “Only allow the server(s) specified above to be in the CTN” at the same time – error message generated Note: Recovery and re-takeover rules unchanged for a CTN with PTS and BTS assigned

IBM Systems © 2013 IBM Corporation Page 6 Rules after applying “Only allow the server(s) specified above to be in the CTN”  If any other server besides the defined PTS, BTS attempts to join the CTN, it will not be allowed to join the CTN  You can disable “Only allow the server(s) specified above to be in the CTN” only if 2 servers communicating over coupling links  You must disable (uncheck) “Only allow the server(s) specified above to be in the CTN” before any of the following actions are allowed: –Any server role assignment changes Includes moving CTS role from PTS to BTS when disruptive action planned on PTS/CTS –A local CTN ID change –A reverse migration from STP-only CTN to Mixed CTN  If you intend to upgrade one of the servers in the CTN to a new machine type, and have it rejoin the same CTN, you must disable (uncheck) “Only allow the server(s) specified above to be in the CTN” before the upgrade, otherwise the server will not be allowed to join the CTN –Example of upgrade: z196 to zEC12

IBM Systems © 2013 IBM Corporation Page 7 Resuming PTS/CTS, BTS roles after outage of both servers  Both servers remain unsynchronized (S0) until they can communicate either over –Coupling link path or –LAN path (Console Assisted Recovery (CAR))  If servers can communicate over coupling link path, –PTS->S1 and BTS->S2  If servers cannot communicate over link paths, but can communicate over LAN path, CAR initiated –Actions taken by PTS If PTS determines BTS is “dead” or S0 –PTS -> S1 –When link paths restored, BTS will become S2 If PTS determines BTS is S1 –PTS -> S0 –When link paths restored, PTS will re-takeover as S1 If PTS cannot determine state of BTS –PTS -> S0

IBM Systems © 2013 IBM Corporation Page 8 Resuming PTS/CTS, BTS roles after outage of both servers (continued) –Actions taken by BTS If BTS determines PTS “dead” –BTS -> S1 –When link paths restored, PTS will become S2 first and re-takeover as S1, if originally assigned CTS If BTS determines PTS operational –BTS -> S0 –When link paths restored, BTS will become S2 If BTS cannot determine state of PTS –BTS -> S0  If servers cannot communicate over link paths and LAN path, –PTS -> S0 –BTS -> S0