When using a hashed shard key mongoD prints the hashed shard key on error messages, instead of printing the plain shard key. The plain shard key is needed to easily identify jumbo chunks.

Wed Nov 27 07:05:53.462 [conn28286] warning: chunk is larger than 67108864 bytes because of key { <SHARD_KEY_NAME
>: -6722522140228250099 }