I have three servers running on amazon aws. each host contains a config server, a mongos instance and a mongod which is part of replica set. All of them save data and logs to ebs RAID10 disc mounted on /ebs folder. Now if i want to take snap shot of the database i will go to on of the host running secondary and will lock the database, snapshot it and then will unlock it. My question is do i need to lock the config sever also? If yes how do i do that? Is it as usual as locking mongodb or not. The RAID consists of 4 discs
The above described is my actual question. But by searching over net and discussion on google groups i found if i am using journal there is no need to lock database. But my question is as i am taking snapshot of discs one after the other until all 4 are completed, how consistency is achieved while writes happen to other discs while i am taking snapshot