Why do you guys always concentrate on the error but forget the environment? -  NW OS and version just to mention the minimal info?

I suppose, this environment has been working before. So why would it fail now?

My personal guess is that the media db is corrupt so that a backup cannot take place any longer. Make sure that you still have enough free disk space on that volume.

nsrck should run smoothly, if possible. Even for several hundreds of clients. However, there are two reasons that will delay the process extremely:

  -  The first step (checking the media index) might hang, depending on the kind of problem.

  -  Checking the file indexes will cause DNS retries for clients which do not exist any longer. I personally have experienced about 30 mins of retries ... per client! - Such has been improved in the past but your version might still be affected. You can avoid that by adding fake entries in the hosts table.

So please check the logs very thoroughly and do not forget: "Good support depends on good input!"