Configure multiple Compute nodes

To distribute your VM load across more than one server, you can connect an additional nova-compute node to a cloud controller node. You can reproduce this configuration on multiple compute servers to build a true multi-node OpenStack Compute cluster.

To build and scale the Compute platform, you distribute services across many servers. While you can accomplish this in other ways, this section describes how to add compute nodes and scale out the nova-compute service.

For a multi-node installation, you make changes to only the nova.conf file and copy it to additional compute nodes. Ensure that each nova.conf file points to the correct IP addresses for the respective services.

By default, nova-network sets the bridge device based on the setting in flat_network_bridge. Update your IP information in the /etc/network/interfaces file by using this template:

# The loopback network interface
auto lo
    iface lo inet loopback

# The primary network interface
auto br100
iface br100 inet static
    bridge_ports    eth0
    bridge_stp      off
    bridge_maxwait  0
    bridge_fd       0
    address xxx.xxx.xxx.xxx
    netmask xxx.xxx.xxx.xxx
    network xxx.xxx.xxx.xxx
    broadcast xxx.xxx.xxx.xxx
    gateway xxx.xxx.xxx.xxx
    # dns-* options are implemented by the resolvconf package, if installed
    dns-nameservers xxx.xxx.xxx.xxx

Restart networking:
```
$ sudo service networking restart
```
Bounce the relevant services to take the latest updates:
```
$ sudo service libvirtd restart
$ sudo service nova-compute restart
```
To avoid issues with KVM and permissions with the Compute Service, run these commands to ensure that your VMs run optimally:
```
# chgrp kvm /dev/kvm
# chmod g+rwx /dev/kvm
```
Any server that does not have nova-api running on it requires an iptables entry so that images can get metadata information.
On compute nodes, configure iptables with this command:
```
# iptables -t nat -A PREROUTING -d 169.254.169.254/32 -p tcp -m tcp --dport 80 -j DNAT --to-destination $NOVA_API_IP:8773
```

Confirm that your compute node can talk to your cloud controller.

From the cloud controller, run this database query:

$ mysql -u$MYSQL_USER -p$MYSQL_PASS nova -e 'select * from services;'

+---------------------+---------------------+------------+---------+----+----------+----------------+-----------+--------------+----------+-------------------+
| created_at          | updated_at          | deleted_at | deleted | id | host     | binary         | topic     | report_count | disabled | availability_zone |
+---------------------+---------------------+------------+---------+----+----------+----------------+-----------+--------------+----------+-------------------+
| 2011-01-28 22:52:46 | 2011-02-03 06:55:48 | NULL       |       0 |  1 | osdemo02 | nova-network   | network   |        46064 |        0 | nova              |
| 2011-01-28 22:52:48 | 2011-02-03 06:55:57 | NULL       |       0 |  2 | osdemo02 | nova-compute   | compute   |        46056 |        0 | nova              |
| 2011-01-28 22:52:52 | 2011-02-03 06:55:50 | NULL       |       0 |  3 | osdemo02 | nova-scheduler | scheduler |        46065 |        0 | nova              |
| 2011-01-29 23:49:29 | 2011-02-03 06:54:26 | NULL       |       0 |  4 | osdemo01 | nova-compute   | compute   |        37050 |        0 | nova              |
| 2011-01-30 23:42:24 | 2011-02-03 06:55:44 | NULL       |       0 |  9 | osdemo04 | nova-compute   | compute   |        28484 |        0 | nova              |
| 2011-01-30 21:27:28 | 2011-02-03 06:54:23 | NULL       |       0 |  8 | osdemo05 | nova-compute   | compute   |        29284 |        0 | nova              |
+---------------------+---------------------+------------+---------+----+----------+----------------+-----------+--------------+----------+-------------------+

In this example, the osdemo hosts all run the nova-compute service. When you launch instances, they allocate on any node that runs nova-compute from this list.

Log a bug against this page

Legal notices