This is a text-only version of the following page on https://raymii.org:

This is a text-only version of the following page on https://raymii.org:
---
Title : Corosync Notes
Author : Remy van Elst
Date : 02-11-2013
URL : https://raymii.org/s/snippets/Corosync_Notes.html
Format : Markdown/HTML
---

What are all the components?

 Recently I removed all Google Ads from this site due to their invasive tracking, as well as Google Analytics. Please, if you found this content useful, consider a small donation using any of the options below: <a href="https://leafnode.nl">I'm developing an open source monitoring app called Leaf Node Monitoring, for windows, linux & android. Go check it out!</a> <a href="https://github.com/sponsors/RaymiiOrg/">Consider sponsoring me on Github. It means the world to me if you show your appreciation and you'll help pay the server costs.</a> <a href="https://www.digitalocean.com/?refcode=7435ae6b8212">You can also sponsor me by getting a Digital Ocean VPS. With this referral link you'll get $100 credit for 60 days. </a> 

* Pacemaker: Resource manager
* Corosync: Messaging layer
* Heartbeat: Also a messaging layer
* Resource Agents: Scripts that know how to control various services

Pacemaker is the thing that starts and stops services (like your database or
mail server) and contains logic for ensuring both that they are running, and
that they are only running in one location (to avoid data corruption).

But it cant do that without the ability to talk to instances of itself on the
other node(s), which is where Heartbeat and/or Corosync come in.

Think of Heartbeat and Corosync as dbus but between nodes. Somewhere that any
node can throw messages on and know that they'll be received by all its peers.
This bus also ensures that everyone agrees who is (and is not) connected to the
bus and tells Pacemaker when that list changes.

If you want to make sure that the commands below execute on all cluster nodes,
append the `-w` parameter to the crm command, it stands for `wait`. Like so:
`crm -w resource stop virtual-ip`.

#### Get corosync cluster status

crm_mon --one-shot -V

or

crm status

#### Put node on standby

Execute on node you want to put in standby.

crm node standby

Put node online again (after standby)

Execute on node you want to put online again.

crm node online

If you want to put a node online or in standby from another cluster node, append
the node name to the commands above, like so:

crm node standby NODENAME

#### Disable stonith (shoot the other node in the head)

crm configure property stonith-enabled=false

#### Add a simple shared IP resource

crm configure primitive failover-ip ocf:heartbeat:IPaddr2 params ip=10.0.2.10 cidr_netmask=32 op monitor interval=10s

This tells Pacemaker three things about the resource you want to add. The first
field, ocf, is the standard to which the resource script conforms to and where
to find it. The second field is specific to OCF resources and tells the cluster
which namespace to find the resource script in, in this case heartbeat. The last
field indicates the name of the resource script.

##### View all available resource classes

crm ra classes

Output:

heartbeat
lsb
ocf / heartbeat pacemaker
stonith

##### View all the OCF resource agents provided by Pacemaker and Heartbeat

crm ra list ocf pacemaker

Output:

ClusterMon Dummy HealthCPU HealthSMART Stateful SysInfo
SystemHealth controld o2cb ping pingd

For Heartbeat:

crm ra list ocf heartbeat

Output:

AoEtarget AudibleAlarm CTDB ClusterMon
Delay Dummy EvmsSCC Evmsd
Filesystem ICP IPaddr IPaddr2
IPsrcaddr IPv6addr LVM LinuxSCSI
MailTo ManageRAID ManageVE Pure-FTPd
Raid1 Route SAPDatabase SAPInstance
SendArp ServeRAID SphinxSearchDaemon Squid
Stateful SysInfo VIPArip VirtualDomain
WAS WAS6 WinPopup Xen
Xinetd anything apache conntrackd
db2 drbd eDir88 ethmonitor
exportfs fio iSCSILogicalUnit iSCSITarget
ids iscsi jboss ldirectord
lxc mysql mysql-proxy nfsserver
nginx oracle oralsnr pgsql
pingd portblock postfix proftpd
rsyncd scsi2reservation sfex symlink
syslog-ng tomcat vmware

#### Add simple apache resource

crm configure primitive apache-ha ocf:heartbeat:apache params configfile=/etc/apache2/apachd2.conf op monitor interval=1min

#### Make sure Apache and the Virtual IP are on the same node

crm configure colocation apache-with-ip inf: apache-ha failover-ip

#### Make sure that when either one crashes they both are recovered on another

node:

crm configure order apache-after-ip mandatory: failover-ip apache-ha

#### Stop a resource

crm resource stop $`RESOURCENAME

#### Delete a resource

crm configure delete $RESOURCENAME

#### Remove a node from the cluster

crm node delete $NODENAME

#### Stop all cluster resources

crm configure property stop-all-resources=true

#### Clean up warnings and errors for a resource

crm resource cleanup $RESOURCENAME

#### Erase entire config

crm configure erase

#### Disable quorum (when using only two nodes)

crm configure property no-quorum-policy=ignore

#### Let the shared IP go back to the primary node when it is up after failover

crom configure rsc_defaults resource-stickiness=100

#### sysctl

In order to be able to bind on a IP which is not yet defined on the system, we
need to enable non local binding at the kernel level.

Temporary:

echo 1 > /proc/sys/net/ipv4/ip_nonlocal_bind

Permanent:

Add this to `/etc/sysctl.conf`:

net.ipv4.ip_nonlocal_bind = 1

Enable with:

sysctl -p

### Sources

* [http://clusterlabs.org/doc/en-US/Pacemaker/1.1-crmsh/html-single/Clusters _from_ Scratch/index.html][2]
* <http://blog.clusterlabs.org/blog/2010/pacemaker-heartbeat-corosync-wtf/>
* <http://blog.clusterlabs.org/blog/2009/highly-available-data-corruption/>
* <http://ourobengr.com/ha/>
* <http://floriancrouzat.net/2013/01/monitor-a-pacemaker-cluster-with-ocfpacemakerclustermon-andor-external-agent/>

[1]: https://www.digitalocean.com/?refcode=7435ae6b8212
[2]: http://clusterlabs.org/doc/en-US/Pacemaker/1.1-crmsh/html-single/Clusters_from_Scratch/index.html

---

License:
All the text on this website is free as in freedom unless stated otherwise.
This means you can use it in any way you want, you can copy it, change it
the way you like and republish it, as long as you release the (modified)
content under the same license to give others the same freedoms you've got
and place my name and a link to this site with the article as source.

This site uses Google Analytics for statistics and Google Adwords for
advertisements. You are tracked and Google knows everything about you.
Use an adblocker like ublock-origin if you don't want it.

All the code on this website is licensed under the GNU GPL v3 license
unless already licensed under a license which does not allows this form
of licensing or if another license is stated on that page / in that software:

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.

Just to be clear, the information on this website is for meant for educational
purposes and you use it at your own risk. I do not take responsibility if you
screw something up. Use common sense, do not 'rm -rf /' as root for example.
If you have any questions then do not hesitate to contact me.

See https://raymii.org/s/static/About.html for details.