Very informative discussion about handling master server crashed in MongoDB master/slave setups:
Alvin Richards: in the case of an unclean shutdown, you must always
- remove the lock file
- start mongod with
- after the repair is complete, then you can restart mongod
The time a repair takes is a function of the amount of data and indexes and the I/O capability of your system. Right now you need access to double the amount of storage as the repair takes place. We will be optimizing this going forward. You can use the
--repairpath to indicate an alternate volume if you need to provision space just for the repair operation.
Original title and link: MongoDB: Handling Master Crashes in Master/Slave Setups (NoSQL databases © myNoSQL)