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How does BRU Server use the ports 14441 to 14450 for backup operations?
BRU Server Port Usage for Backup Operations
BRU Server uses TCP ports 14441 to 14450. These ports cannot be changed by the user.
In order to understand how BRU Server uses ports, both during backups and when dormant, this article discusses the uses of the ports and how the parent-child port relationship occurs as well as the BRU process that you may see running in the process list. To make it easier to understand, we will only use two machines - the BRU Server Server system and the BRU Server Agent system.
The BRU Server Server is the main system that has BRU Server's Server component, the BRU Server Agent component, and possibly the BRU Server Console installed. The BRU Server Agent system is the client machine that has only the BRU Server Agent software installed.
While BRU Server is running, but not actually performing a backup, the following ports are used:
Port 14441 is in use by the BRU Server "Server" process, listening for connections from the BRU Server Console, bru-server.cmd, or bru-server.console applications. Port 14442 is in use on both the client machine that has the BRU Server Agent software installed, as well as the BRU Server Server system, because it too has the BRU Server Agent software installed. Port 14441 will always be in use as long as the BRU Server's Server daemon is running, as will the BRU Server Agent process on 14442. No other ports are currently in use.
Now, lets start a backup of the BRU Server Agent system. This backup will be called "Backup 1". The type of backup does not matter because no matter what type of backup it happens to be, the same process is used. With "Backup 1" now running, the following ports are used:
BRU Server Server: Ports 14441 and 14442 are still in use, however, now port 14443 is in use to receive the data for the "Backup 1" backup job from the BRU Server Agent system.
Now a scheduled backup on the BRU Server Server has started. That job name is "Backup 2" and it's backing up the BRU Server Server system.
BRU Server Server: All previous ports are the same, however, now port 14444 is sending the data to port 14445 for the backup of the BRU Server Server system.
Now, to get a better idea of how the backup processes are spawned, lets start another backup operation on the BRU Server Agent system. In doing so, you will now see the port usage as:
BRU Server Server: All previous ports are still the same, however, now port 14446 has been put to use to receive the data from "Backup 3" on the BRU Server Agent system.
If you continue this process, you can see how each backup takes a port on the Server system and on the Agent system.
How does the parent-child relationship come into play with all of this? It's actually quite simple. First, the question must be asked "what is a parent-child relationship when it comes to TCP/IP ports?" A parent port is the initial process that spawns other processes and a child process is the spawned process. Therefore, in the example below, the parent Server process is using port 14441. This process is the first one created by BRU Server's Server component when the BRU Server Server daemon was started.
The parent-child relationship is on a per-machine basis. Therefore, the Agent Child on the BRU Server Agent for "Backup 3" is not the child of any processes on the BRU Server Server system. This is because that would cross machines, which the parent-child relationship does not do. Instead, the parent-child relationship is individually done for each machine. The parent process of "Backup 3" on the BRU Server Agent system is the Agent process that using port 14442.
Process tree's can be viewed in a Unix command line. To do this, simply execute "ps axjf". You can also sort the list by using the "grep" command, such as "ps axjf | grep bru". That command requests the process tree list, but only shows those with the name of "bru" in the command.
Here is an example process tree from a Unix system with one backup process running to a tape device and only showing the process with the name of "bru":
$ ps axjf | grep bru
In the above example, there are three parent processes. Process 2587, 2589, and 12047. The processes listed below each are "child" processes that have been spawned from the parent process.
For questions about this, or for further cliarification, please contact Technical Support.