db.fsyncLock() in mongodb

db.fsyncLock() 

This method forces the mongod to flush all pending write operations to disk and locks the entire mongod instance to prevent additional writes until the user releases the lock with the db.fsyncUnlock() command.

Note: db.fsyncLock() is an administrative command.

Example

MongoDB

db.fsyncLock()

Output:

{
        "info" : "now locked against writes, use db.fsyncUnlock() to unlock",
        "lockCount" : NumberLong(1),
        "seeAlso" : "http://dochub.mongodb.org/core/fsynccommand",
        "ok" : 1
}