A quick note on MongoDB replica sets

by Rob Martin on

Highly readable version

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 directive[1] in my mongod.conf. The file itself contains a base64 text key the servers will use for communicating.

keyFile = /etc/mongodb/key.txt

  1. See the "Replica Set and Sharding Authentication" section on the MongoDB doc page for Security and Authentication.

Talk back to me

You can comment below. Or tweet at me. I'm always open to a good conversation.