A quick note on MongoDB replica sets

Tue 29 Nov 2011

MongoDB is replying to a replica-set add command with “Need most members up to reconfigure, not ok”. The problem is with my configuration.

Here’s the error:

PRIMARY> rs.add("nosql1-private:27017")
{
    "assertion" : "need most members up to reconfigure, not ok : nosql1-private:27017",
    "assertionCode" : 13144,
    "errmsg" : "db assertion failure",
    "ok" : 0
}

The problem is in my configuration on the slave Mongod. Note that I’m using a configuration file, rather than command line options, which is how the tutorials are written. This fits in with my init file, which I can share if anyone wants an Ubuntu init for MongoDB 2.0.2.

fork = true
bind_ip = nosql1-private
port = 27017 # default port
logpath = /var/log/mongodb/mongod.log
logappend = true
cpu = true # log CPU activity periodically
journal = true
auth = true
replSet = gedc

I disabled journal (shouldn’t be needed on a slave, right?) and auth, which seems to actually be the problem. After, the rs.add() works fine.

PRIMARY> rs.add("nosql1-private:27017")
{ "ok" : 1 }

I’m not sure I don’t have to go back and get auth reenabled, though, because now my status says that the second server is “still initializing” and “(not reachable/healthy)”. But when I try to add authentication credentials, I get this error:

uncaught exception: error { "$err" : "not master and slaveok=false", "code" : 13435 }

So, I did discover what I really needed was a keyFile directive¹ in my mongod.conf. The file itself contains a base64 text key the servers will use for communicating.

...
keyFile = /etc/mongodb/key.txt
...