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Can Tomcat be configured within a Cold Standby configuration?

Christopher Guild (3613) | asked Nov 08 '12, 12:51 p.m.
Planning idle standby deployment discusses a cold standby configuration with Jazz™ Team Server using WebSphere® Application Server.  Would there be a possibility that Tomcat supports a similar configuration?

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Christopher Guild (3613) | answered Nov 08 '12, 1:05 p.m.
edited Nov 08 '12, 1:19 p.m.
Yes, provided that the configuration is tested and confirmed.  The highlights from the URL above is as follows:

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Differences between idle standby and cold standby
As you are planning your standby configuration, you should consider whether to have an idle standby or a cold standby environment for your applications.  Cold standby refers to having backup servers in place with installed applications in a stopped state, while idle standby comprises backup servers with installed applications already started and in an idle state.  Following are a few key considerations for each environment:

Manual failover with backup: Applications not started (cold standby)
   1)  The applications in the backup servers will be in a stopped state.
   2)  It is simpler to setup. You clone the Primary server after it is provisioned and configured.   <--  THIS IS CRITICAL that the systems are "identically cloned"
   3)  Configuration updates made on the Primary server can be propagated by a simple file synchronization using rsync or other utilities.
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However, in a Cold Standby configuration, the backup system is usually powered off and remains dormant.  One way to keep the following files synchronized would be to have easily configurable local storage (SAN, iSCSI, external array) that has be quickly switched between the systems (HBA, network, SCSI / eSATA):

   (if it exists) JazzInstallDir/server/tomcat/webapps/ccm/WEB-INF/web.xml
   (if it exists) JazzInstallDir/server/tomcat/webapps/clmhelp/WEB-INF/web.xml
   (if it exists) JazzInstallDir/server/tomcat/webapps/converter/WEB-INF/web.xml
   (if it exists) JazzInstallDir/server/tomcat/webapps/jazz/WEB-INF/web.xml
   (if it exists) JazzInstallDir/server/tomcat/webapps/jts/WEB-INF/web.xml
   (if it exists) JazzInstallDir/server/tomcat/webapps/qm/WEB-INF/web.xml
   (if it exists) JazzInstallDir/server/tomcat/webapps/rm/WEB-INF/web.xml

Thus, if either the system root directory including the JazzInstallDir are covered under the direct attached storage or at least both systems are configured identically and only the JazzInstallDir path is covered under the direct attached storage, switching between systems should be possible.

To summarize:
  • Have a copy of the configuration files on the cold standby server
  • Make sure the cold standby server is accessible with the host name matching your public URI once the original server is down
  • Have a working Database and consistent index files accessible in the location used in the configuration files
            NOTE:  See for which files are important.

Above all:  PLEASE TEST before implementing within a live production environment.

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