Multiple Mongos on one server

Question

I'm not talking about sharding. We had a testing server (linux) and there is already one mongo which belongs to another project/subteam. Is it possible to run multiple, isolated instances of mongodb on one machine? How can I do it?

Answer 1

Yes, you can do this by specifying different port numbers and data directories for the other instances of mongod, and then specifying the new port number in the client.

For example:

./mongod --dbpath /foo/bar/otherpath --port some_other_port

You can also change the shard server and config server port numbers if you need to.

Answer 2

The steps I've taken are:

1. Copy conf file /etc/mongod.conf to mongod2.conf and also to mongod3.conf
2. Edit conf files to have different ports and different database paths
3. Copy init.d start script /etc/init.d/mongod to mongod2 and also to mongod3
4. Copy binary mongod /usr/bin/mongod to /usr/bin/mongod2 and also to /usr/bin/mongod3

5. Edit init.d start scripts and changed the following:

   CONFIGFILE="/etc/mongod2.conf" (mongod3.conf, respectively)

   ....

   mongod=${MONGOD-/usr/bin/mongod2} (mongod3, respectively)

Replaced /var/lock/subsys/mongod with /var/lock/subsys/mongod2 (mongod3, respectively) wherever I found it.

Resist the temptation to replace mongod.lock with mongod2.lock (or to mongod3.lock, respectively). They are in different folders (database folders are different) and won't conflict.

Now I can

service mongod start|stop|status

service mongod2 start|stop|status

service mongod3 start|stop|status

and also

mongo --port <port_number> 

for each mongo instance (remember the port settings from the conf files)

I am not aware of any side effect of renaming the mongod binary..

Hope this helps.

[Later edit] To start the instances automatically, just ln -s /etc/init.d/mongod2 /etc/rc.d/rc3.d/S86mongod and ln -s /etc/init.d/mongod3 /etc/rc.d/rc3.d/S87mongod :)