To prevent Redgate Monitor from interfering with critical system processes, DEADLOCK_PRIORITY  has been set to its lowest possible value. In the event that a deadlock occurs, SQL Server will always choose the Redgate Monitor sampler query as the victim instead of essential system operations.  Redgate Monitor is designed to be able to handle occasional deadlocks and so this will not impact monitoring unless it occurs every time the sampler runs.

If alerts are being raised for these deadlocks here are some possible solutions:

• Ensure the samplers are running at a different frequency and time to the backups. 
• Set Redgate Monitor to not raise alerts for those deadlocks, by editing the Configuration > Alert settings for the Deadlock alert.  An exclusion can be added based on the login (for the user Redgate Monitor is using to connect) or with "resources matching" (E.g. backupmediaset OR backupset).
• Change the sampling frequency (such as 7 mins instead of 5 mins), through ConfigurationFileEditor.exe tool included in the Tools subdirectory of the base monitor installation directory (C:\Program Files\Red Gate\Redgate Monitor\BaseMonitor\Tools by default):
  
  • Right click and run the tool as an Admin.
  • Click on the Load Configuration File option and then select the "RedGate.Monitor.BaseMonitor.exe.settings.config" which should be residing under the C:\ProgramData\Red Gate\Redgate Monitor directory by default.
    • It's recommended that you save a copy of the configuration file elsewhere before editing it further.
  • Once you've loaded the configuration file, scroll down and tick the box next to each [Cluster].[SqlServer].[Database].[Database].[BackupType] and [Cluster].[SqlServer].[Database].[Database][BackupType].[Backup] and then change the 5 in the "Minutes" section to the desired frequency as seen below:
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  • Save the configuration file using the disk icon at the top left and then restart the "Redgate Monitor Base Monitor" Windows service. This should reduce the occurrence of the deadlocks.