Confirming MongoDB replica set and arbiter

[integrativeadmin]

I think I successfully created a mongodb replica set with an arbiter.  When I run rs.status() on the primary, I get the following:

    rs0:PRIMARY> rs.status()

    {

    "set" : "rs0",

    "date" : ISODate("2013-10-23T15:11:27Z"),

    "myState" : 1,

    "members" : [

    {

    "_id" : 0,

    "name" : "10.50.1.10:27017",

    "health" : 1,

    "state" : 1,

    "stateStr" : "PRIMARY",

    "uptime" : 71210,

    "optime" : Timestamp(1382539219, 1),

    "optimeDate" : ISODate("2013-10-23T14:40:19Z"),

    "self" : true

    },

    {

    "_id" : 1,

    "name" : "10.50.3.10:27017",

    "health" : 1,

    "state" : 2,

    "stateStr" : "SECONDARY",

    "uptime" : 2362,

    "optime" : Timestamp(1382539219, 1),

    "optimeDate" : ISODate("2013-10-23T14:40:19Z"),

    "lastHeartbeat" : ISODate("2013-10-23T15:11:26Z"),

    "lastHeartbeatRecv" : ISODate("2013-10-23T15:11:26Z"),

    "pingMs" : 1,

    "syncingTo" : "10.50.1.10:27017"

    },

    {

    "_id" : 2,

    "name" : "mongodb2.iin:30000",

    "health" : 0,

    "state" : 8,

    "stateStr" : "(not reachable/healthy)",

    "uptime" : 0,

    "lastHeartbeat" : ISODate("2013-10-23T15:11:26Z"),

    "lastHeartbeatRecv" : ISODate("1970-01-01T00:00:00Z"),

    "pingMs" : 0

    }

    ],

    "ok" : 1

Towards the bottom, the arbiter is showing as stateStr : not reachable/healthy.  Is that normal?  

I plan on testing the replica set by simulating a failover process by shutting down the primary and see it failover.  I would shut down the primary and then log into the slave and it should eventually be the primary, correct?  What's the best practice in having the MongoDB automatically startup upon a reboot?  I'm using a config file so I would need to add the command "mongod --config /etc/mongodb.conf" to a bash script and execute on boot?

[Russell Bateman]

Yes, that's what I would expect for the arbiter.

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[CC XW]

Hi,integrativeadmin  ,

   I have got the same error. I have 2 replica sets. Each has two members -Primary and Secondary. Alter I  used rs.addArb() to add the arbiter to each replicaSet with no problem. All the mongod services are running fine.

   I run rs.config() and rs.status(). I got the same status : (not reachable/healthy).

   Have you figured out how to get out of this status?

   I am using Mongod 2.6.7 on Unix servers.

   Please share your information in advance.

   Thank you!

CC XW

[Dwight Merriman]

not reachable is not normal.

can you connect to the arbiter with the mongo shell?  

On Wednesday, October 23, 2013 at 12:03:40 PM UTC-4, integrativeadmin wrote:

[Alberto Frosi]

Normally in these cases host could have a network issue.

[Alberto Frosi]

...or wrong host name or port in RS.addArb command.

[CC XW]

But, I could see the process is up running. I could even connect to it (arbiter) using mongo -port .

After I issue the command

rs.addArb("devrs1/MyHost01.mydomain.com:27028");
I got the result like this

{
    "down" : [
        "devrs1/MyHost01.mydomain.com:27028"
    ],
    "ok" : 1
}

[Alberto Frosi]

Mmm very strange, can you take a look in arbiter log ?

I ran a small test in my VM with 1P, 2S and 1 Arb:

mongod --smallfiles --oplogSize 50 --port 27008 --dbpath z1 --replSet z --fork --logpath z1/a.log

mongod --smallfiles --oplogSize 50 --port 27009 --dbpath z2 --replSet z --fork --logpath z2/b.log

mongod --smallfiles --oplogSize 50 --port 27010 --dbpath z3 --replSet z --fork --logpath z3/c.log

mongod --fork --logpath arb/arb.log --port 30000 --dbpath arb --replSet z

I add the member in replica set and the arbiter, initiate replica and all work fine

MongoDB shell version: 2.6.4

connecting to: 127.0.0.1:27008/test

z:PRIMARY> 

z:PRIMARY> 

z:PRIMARY> rs.addArb("m202-ubuntu1404:30000")

{ "ok" : 1 }

z:PRIMARY> rs.config()

{

"_id" : "z",

"version" : 4,

"members" : [

{

"_id" : 0,

"host" : "m202-ubuntu1404:27008"

},

{

"_id" : 1,

"host" : "m202-ubuntu1404:27009"

},

{

"_id" : 2,

"host" : "m202-ubuntu1404:27010"

},

{

"_id" : 3,

"host" : "m202-ubuntu1404:30000",

"arbiterOnly" : true

}

]

}

z:PRIMARY> rs.status()

{

"set" : "z",

"date" : ISODate("2015-03-27T08:32:54Z"),

"myState" : 1,

"members" : [

{

"_id" : 0,

"name" : "m202-ubuntu1404:27008",

"health" : 1,

"state" : 1,

"stateStr" : "PRIMARY",

"uptime" : 629,

"optime" : Timestamp(1427445157, 1),

"optimeDate" : ISODate("2015-03-27T08:32:37Z"),

"electionTime" : Timestamp(1427444638, 2),

"electionDate" : ISODate("2015-03-27T08:23:58Z"),

"self" : true

},

{

"_id" : 1,

"name" : "m202-ubuntu1404:27009",

"health" : 1,

"state" : 2,

"stateStr" : "SECONDARY",

"uptime" : 369,

"optime" : Timestamp(1427445157, 1),

"optimeDate" : ISODate("2015-03-27T08:32:37Z"),

"lastHeartbeat" : ISODate("2015-03-27T08:32:53Z"),

"lastHeartbeatRecv" : ISODate("2015-03-27T08:32:54Z"),

"pingMs" : 0,

"syncingTo" : "m202-ubuntu1404:27008"

},

{

"_id" : 2,

"name" : "m202-ubuntu1404:27010",

"health" : 1,

"state" : 2,

"stateStr" : "SECONDARY",

"uptime" : 362,

"optime" : Timestamp(1427445157, 1),

"optimeDate" : ISODate("2015-03-27T08:32:37Z"),

"lastHeartbeat" : ISODate("2015-03-27T08:32:54Z"),

"lastHeartbeatRecv" : ISODate("2015-03-27T08:32:53Z"),

"pingMs" : 0,

"syncingTo" : "m202-ubuntu1404:27008"

},

{

"_id" : 3,

"name" : "m202-ubuntu1404:30000",

"health" : 1,

"state" : 7,

"stateStr" : "ARBITER",

"uptime" : 17,

"lastHeartbeat" : ISODate("2015-03-27T08:32:53Z"),

"lastHeartbeatRecv" : ISODate("2015-03-27T08:32:53Z"),

"pingMs" : 0

}

],

"ok" : 1

}

z:PRIMARY> exit

[AP]

I had a same issue as described in the OP. I figured out that was because of the journal and small files settings (as described in the consideration section here). I had put "journal=false" and "smallFiles=true" for my arbiter which seems to be a fine thing to do and was abl to start arbiter service with no issues. But after adding arbiter to replica set with other replicas the rs.status() was showing "arbiter => stuats(8): not reachable/healthy". It started showing stateStr as "ARBITER" ans state as 7 once I removed journal and smallfiles settings from conf. For some reason just modifying the conf didn't work. Had to delete the service and re-create it. But it worked. I wonder why these two recommended settings didn't work! 

Don't know if it is the right thing... but it worked! Hope it helps!