Additional server considerations and troubleshooting

Automatic installation

You can automate the installation with Ansible, Chef, or Puppet. Click the link below for more detailed information.

Performance considerations

The AppMon Frontend Server provides the data to the connected Clients for analysis. This way the original AppMon Server has more headroom to gather and correlate data from the Collectors.

The AppMon Server requires disk storage for recorded sessions. By default, the directory used for stored sessions is in the installation directory as previously shown. You may need to relocate this directory to a high-performance I/O device or a high-volume device to increase the Server's performance when working intensively with stored sessions. You can:

  • Mount a designated volume to that directory or create a symbolic link to another volume.
  • Change configuration settings to point to a different directory in the client by selecting Settings > Dynatrace Server > Storage.

Memory and CPU requirements are covered in detail in the Deployment Guide.

Versioned profiles

All System Profiles are stored in the profiles folder as XML files (ending with .profile.xml). Those files should not only be backed up on a regular basis but can also be archived with common version control systems. Doing so provides easy history control and rollback over the course of time.

Parallel startup of server and analysis server

If you have the AppMon Server and AppMon Analysis Server installed on the same machine (sharing the same core executables), it is not possible to start both servers at the same time, for example by using a Unix shell script.

In this case, possible solutions are:

  • Install the Analysis Server standalone on the machine, or
  • In your shell script, first start the Analysis Server, wait a short time (typically 10 seconds suffices) and then start the AppMon Server.

Number of open files limit on Linux

Some Unix-based systems impose a rather low limit on the number of files or file descriptors a user or process can have open. This limit includes open socket connections.

Because the AppMon Server needs to read/write many files from/to the session store and have many socket connections open, the system default limits for the number of open files may be too low. Some Linux distributions use a default of 1024 file handles, which is most likely too low for medium to large AppMon installations. Therefore, the AppMon server enforces a minimum of 2048 file handles. Use ulimit -n to query the current number of file handles.

Note

Don´t confuse the ulimit (thousands) with the system-wide limit (hundreds of thousands) that you can check with more /proc/sys/fs/file-max.

You may learn of an insufficient limit through an error message like IOException: Too many open files or java.net.SocketException: Too many open files. Before changing anything, check the current (soft) limit with ulimit -n or ulimit -Sn. Use ulimit -Hn to determine how much you can raise it as non-root.

Use ulimit -n <numberOfFileDescriptors> to raise the (soft) limit temporarily for the current user. Add entries for other users / groups to /etc/security/limits.conf. Use ulimit -n to check that the change was successful.