Adding members to Replica Set on MongoDb

Question

I am trying to create a replica set with MongoDb, the servers hostnames are:

hostname hostname-1 hostname-2

Each of these has all the relevant hostnames detailed in their /etc/hosts file (They;re all running Ubuntu 10.04 64-bit)

When I do an rs.initiate on one node everything seems to start well. Running rs.status(); shows:

{
    "set" : "vega",
    "date" : ISODate("2012-01-22T19:15:55Z"),
    "myState" : 1,
    "members" : [
        {
            "_id" : 0,
            "name" : "hostname:27017",
            "health" : 1,
            "state" : 1,
            "stateStr" : "PRIMARY",
            "optime" : {
                "t" : 1327254848000,
                "i" : 1
            },
            "optimeDate" : ISODate("2012-01-22T17:54:08Z"),
            "self" : true
        }
    ],
    "ok" : 1
}

The problem comes when I try to add a new member to the replica set. I use the command rs.add(hostname-1); and I get the following error:

{
    "assertion" : "need most members up to reconfigure, not ok : vega-1:27017",
    "assertionCode" : 13144,
    "errmsg" : "db assertion failure",
    "ok" : 0
}

I've tried numerous combinations of using the hostname, IP address, both with and without the port number and I always get the same problem. The hostname is resolving, i've tried ping hostname-1 and it works fine.

Does anybody have any ideas as to what could be causing this issue?

Unfortunately in the Mongo documentation there are no examples of setting up a replica set in the real world scenario, only using three instances on the same machine which is clearly useless.

Thanks in advance for any help!

Answer 1

Remove this in your configuration:

bind_ip = 127.0.0.1

That option is currently incompatible with mongodb replica sets.

Answer 2

That error happens when you're adding nodes that aren't "up" (yet). It sounds like either "hostname-1" is unreachable (not in /etc/hosts, no DNS) or it is reachable but isn't running mongodb with the replSet configuration parameter set