Yes, but there are some significant caveats. First off, the users that are logged on to the CICS TOR on the failing system will be knocked off and have to log back on. Assuming there's a VTAM generic in place, that should be no big deal--they'll get directed to the surviving TOR and can continue to work once they log back in. If you're coming in via IP via WAS or even a direct socket, there are options for similarly routing people to the surviving member.
However, any locks that the failing DB2 had in place are retained until that DB2 member is restarted. You can automate the restart of that DB2 on the surviving system to speed that process up, but the time it takes to do that is non-zero and related to how much activity was in- flight at the time of the failure. Application design is what really impacts the availability of the application during the failure. For example, it's not uncommon for applications to update a common table, and even sometimes a common row in that table, for most or all transactions. In that case, it's quite possible for the DB2 that failed to have held a lock on that common resource. That could prevent the application from running until that lock is resolved--that is until the failing DB2 is restarted. And of course if the application has affinities life may be worse. E.G. even our most sysplex- friendly app still uses a single DOR for some file access and still has affinities to particular MQs. So if the system failure impacts those resources, those tasks need to be restarted before the application can continue. Getting those affinities removed is an uphill battle because we take almost no unplanned system outages these days, so there's very little payback for resolving them. For planned outages we shift those resources to another system at a convenient time. I hope that helps. Scott Chapman >Can you set up a sysplex so that both machines have everything running on >each CPU in the plex, and when one system crashes the other will >automatically take over everything? Say you have SYSA and SYSB. Each has >10 CICS regions running. Half of the applications are routed to SYSA, and >the other half to SYSB, but all 10 CICS regions are running on each system. >If SYSA crashes, can all transactions now be routed to SYSB? I'm sure that >any transactions on SYSA at the time of the crash will not finish, and have >to be reentered, but I was under the impression that everything after the >crash could then be routed to SYSB after the SYSA crash. I'm not sure if >that could be done automatically by automation, or would take someone to >look at it and type in a command. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
