The logging of balancer operations, along with associated warnings and errors, is currently distributed across the entire shard cluster. As a result, the only way to get a complete picture of what's going on with a shard cluster is to examine the log files generated by all the various mongos and mongod processes therein.

This results in a lot of time spent diagnosing even simple issues.

It'd be nice if we could log all major sharding operations and errors to a central collection located in the config servers. This would greatly simplify monitoring and investigating the cluster as a whole.