I agreed Flavio that we should let admin guys be aware of why the bookie can't start and how they should do when encountering such cases. I would suggest moving the detail cookie format to bookkeeper internal documents, and add some trouble shooting guideline in administrator guide so admin guys know how to handle when encountering similar cases.
There are multiple reasons that could lead to a bookie to not start. Wiping out a directory by either replacing a disk or accidentally deleting it are two reasons. In such cases, I'm not entirely sure of what the troubleshooting procedure is right now. Is it to wipe out the whole bookie state and reconstruct its state from scratch by using the bookie recovery tool? If this is something that we will better handle in 4.2.0, we may want to point out that the current version does not provide a feature that handles nicely such situations and it will come in a future version.
In any case, it sounds like a good idea to me to have a section in the admin's guide called "Troubleshooting".
do we have any guidelines that when to run bookie recover tool?
In the docs folder, we have bookieRecovery.textile. It seems to be missing the case in which we have the target bookie as part of the input.