remove a mongodb replica set when into a sharding cluster

Question

I have this configuration:

mongos> db.adminCommand('getShardMap')
{
"map" : {
    "RS13" : "RS13/mongo09-02:27003,mongo09-01:27001",
    "RS13/mongo09-02:27003,mongo09-01:27001" : "RS13/mongo09-02:27003,mongo09-01:27001",
    "RS26" : "RS26/mongo09-04.de.prod:27008,mongo09-01:27002",
    "RS26/mongo09-04.de.prod:27008,mongo09-01:27002" : "RS26/mongo09-04.de.prod:27008,mongo09-01:27002",
    "RS45" : "RS45/mongo09-02:27004,mongo09-03:27005",
    "RS45/mongo09-02:27004,mongo09-03:27005" : "RS45/mongo09-02:27004,mongo09-03:27005",
    "RS67" : "RS67/mongo09-03:27006,mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "RS67/mongo09-03:27006,mongo09-03.de.prod:27006,mongo09-04.de.prod:27007" : "RS67/mongo09-03:27006,mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "config" : "mongo09-01:27011,mongo09-02:27012,mongo09-03:27013",
    "mongo09-01:27001" : "RS13/mongo09-02:27003,mongo09-01:27001",
    "mongo09-01:27002" : "RS26/mongo09-04.de.prod:27008,mongo09-01:27002",
    "mongo09-02:27003" : "RS13/mongo09-02:27003,mongo09-01:27001",
    "mongo09-02:27004" : "RS45/mongo09-02:27004,mongo09-03:27005",
    "mongo09-03.de.prod:27006" : "RS67/mongo09-03:27006,mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "mongo09-03:27005" : "RS45/mongo09-02:27004,mongo09-03:27005",
    "mongo09-03:27006" : "RS67/mongo09-03:27006,mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "mongo09-04.de.prod:27007" : "RS67/mongo09-03:27006,mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "mongo09-04.de.prod:27008" : "RS26/mongo09-04.de.prod:27008,mongo09-01:27002"
},
"ok" : 1
}

Actually mongo09-03 it seems to be duplicated:

    "mongo09-03.de.prod:27006" : "RS67/mongo09-03:27006,mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "mongo09-03:27006" : "RS67/mongo09-03:27006,mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",

And please consider replica set RS67 is also part of a sharding cluster.

May I remove a mongodb replica set when it is into a sharding cluster ? And if yes, how?

Can I use rs.remove(hostname) ?

Mike · Answer 1 · 2013-03-27T01:43:40.683

1

It isn't an easy run one command type thing. See the following on the doc site

http://docs.mongodb.org/manual/tutorial/remove-shards-from-cluster/

To remove a replicaset member

 rs.remove("mongo09-03.de.prod:27006")

edited Mar 27 '13 at 01:43

answered Mar 27 '13 at 01:19

Mike

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Thanks Mike, I would like to know if I can remove only one host from the replica sets leaving the sharding cluster alive – freedev Mar 27 '13 at 01:21
yes you can do that. As since there are at least 2 nodes + arbiter in the replicaset.. at least one will contain the data. Then it is as simple as a single command – Mike Mar 27 '13 at 01:25
Do you know which command? Could we use `db.shards.update({_id: "RS67"} , {$set: {"host" : "RS67/mongo09-03.de.prod:27006,mongo09-04.de.prod:27007"}})` ? – freedev Mar 27 '13 at 01:27
I updated my answer – Mike Mar 27 '13 at 01:43
Thanks Mike, actually waiting I have successfully tried with `db.shards.update...`. Anyway +1 thanks for your support :) – freedev Mar 27 '13 at 01:53

freedev · Answer 2 · 2013-03-28T12:01:28.200

We have successfully configured the replica set executing this command:

db.shards.update({_id: "RS67"} , {$set: {"host" : "RS67/mongo09-03.de.prod:27006,mongo09-04.de.prod:27007"}})

The shard map now it is correctly configured and extra mongo09-03 has been disappeared.

mongos> db.adminCommand('getShardMap') 
{
"map" : {
    "RS13" : "RS13/mongo09-02:27003,mongo09-01:27001",
    "RS13/mongo09-02:27003,mongo09-01:27001" : "RS13/mongo09-02:27003,mongo09-01:27001",
    "RS26" : "RS26/mongo09-04.de.prod:27008,mongo09-01:27002",
    "RS26/mongo09-04.de.prod:27008,mongo09-01:27002" : "RS26/mongo09-04.de.prod:27008,mongo09-01:27002",
    "RS45" : "RS45/mongo09-02:27004,mongo09-03:27005",
    "RS45/mongo09-02:27004,mongo09-03:27005" : "RS45/mongo09-02:27004,mongo09-03:27005",
    "RS67" : "RS67/mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "RS67/mongo09-03.de.prod:27006,mongo09-04.de.prod:27007" : "RS67/mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "config" : "mongo09-01:27011,mongo09-02:27012,mongo09-03:27013",
    "mongo09-01:27001" : "RS13/mongo09-02:27003,mongo09-01:27001",
    "mongo09-01:27002" : "RS26/mongo09-04.de.prod:27008,mongo09-01:27002",
    "mongo09-02:27003" : "RS13/mongo09-02:27003,mongo09-01:27001",
    "mongo09-02:27004" : "RS45/mongo09-02:27004,mongo09-03:27005",
    "mongo09-03.de.prod:27006" : "RS67/mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "mongo09-03:27005" : "RS45/mongo09-02:27004,mongo09-03:27005",
    "mongo09-04.de.prod:27007" : "RS67/mongo09-03.de.prod:27006,mongo09-04.de.prod:27007",
    "mongo09-04.de.prod:27008" : "RS26/mongo09-04.de.prod:27008,mongo09-01:27002"
},
"ok" : 1
}

please also consider that:

The list of hosts in the collection is only used when mongos first starts up, as a seed list. Once the process starts they auto-discover the rest of the members (just like any other client/driver in replica set mode) and keep track of each member in the replica set.

remove a mongodb replica set when into a sharding cluster

2 Answers2