Producing Data Files for System Recovery

Save these files, because they are valuable for troubleshooting.

When a problem arises that involves more than one process, a network problem is the most likely cause. When you diagnose a problem, create a log file for each member of all the distributed systems involved. If you are running a client/server architecture, create log files for the clients.

Note: You must run a time synchronization service on all hosts for troubleshooting. Synchronized time stamps ensure that log messages on different hosts can be merged to accurately reproduce a chronological history of a distributed run.
For each process, complete these steps:
  1. Make sure the host’s clock is synchronized with the other hosts. Use a time synchronization tool such as Network Time Protocol (NTP).
  2. Enable logging to a file instead of standard output by editing to include this line:

  3. Keep the log level at info to avoid filling up the disk. Add this line to

    Note: Running with the log level at fine impacts system performance and can fill up your disk.
  4. Run the application again.
  5. Examine the log files. To get the clearest picture, merge the files. To find all the errors in the log file, search for lines that begin with this string:


    For details, see the merge-logs command in vFabric GemFire Command-Line Utility.