markap14 commented on pull request #5438: URL: https://github.com/apache/nifi/pull/5438#issuecomment-936447902
@sdairs depending on the operating system, hardware, etc. in many environments, we can create & write files faster than we can delete them. As a result, we can have a situation where we create a lot of files in the content repository - so much so that we cannot keep up with deleting data that's no longer needed, and we can start running out of disk space. To prevent this, we have a backpressure mechanism where the content repo decides that the threshold has been reached, so it's not going to allow any new FlowFIles to be written until a background thread has had a chance to archive or destroy unneeded data in the content repository. So those 2 properties work together. When `nifi.content.repository.archive.backpressure.percentage` is reached, it applies backpressure and prevents writing until the background thread reduces disk usage to below the `nifi.content.repository.archive.max.usage.percentage` threshold. So if `nifi.content.repository.archive.max.usage.percentage` is set to 50%, and `nifi.content.repository.archive.backpressure.percentage` is set to 60% it will allow content to be written until repo is 60% full. Then it will prevent it until repo is less than 50% full. If `nifi.content.repository.archive.backpressure.percentage` is not set, it defaults to 2% more than `nifi.content.repository.archive.max.usage.percentage`. So 52% by default. Or, said another way - they function together as the low-water mark & high-water mark :) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
