EDB Postgres Failover Manager (EFM) is a high-availability module from EnterpriseDB that enables a Postgres Master node to automatically failover to a Standby node in the event of a software or hardware failure on the Master.
In this blog I am trying my best to explain how to Install,Configure and Perform [Failover/Switchover] .
You can get EDB's official document from - Link
Supported Platforms
Failover Manager 3.2 is supported on EDB Postgres Advanced Server or PostgreSQL(version 9.3 and higher) installations running on:
CentOS 6.x and 7.x
Red Hat Enterprise Linux 6.x and 7.x
Above command opens a small range of ports (7800 through 7810). Failover Manager will connect via the port that corresponds to the port specified in the cluster properties file.
Edit below file
Install EFM 3.2
Keep copy of this password for some time .
4) Make a configuration files .
After installation two sample files get created i.e
a) efm.property.in
b) efm.nodes.in
Make a copy of this file as
cp /etc/edb/efm-3.2/efm.properties.in /etc/edb/efm-3.2/efm.properties
cp /etc/edb/efm-3.2/efm.nodes.in /etc/edb/efm-3.2/efm.nodes
efm.nodes file contains a list of the current Failover Manager cluster members.
In this blog I am trying my best to explain how to Install,Configure and Perform [Failover/Switchover] .
You can get EDB's official document from - Link
Supported Platforms
Failover Manager 3.2 is supported on EDB Postgres Advanced Server or PostgreSQL(version 9.3 and higher) installations running on:
CentOS 6.x and 7.x
Red Hat Enterprise Linux 6.x and 7.x
Oracle Enterprise Linux 6.x and 7.x
Red Hat Enterprise Linux (IBM Power8 Little Endian or ppc64le) 7.x
Debian 9
SLES 12
Ubuntu 18.04
Prerequisites
1) Install Java-1.8 or later
2) Configure Streaming Replication
3) Make sure below ports are open .
iptables -I INPUT -p tcp --dport 7800:7810 -j ACCEPT
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Above command opens a small range of ports (7800 through 7810). Failover Manager will connect via the port that corresponds to the port specified in the cluster properties file.
So ,Now let's start with actual installation and configuration of EFM considering you have a fresh system .
Download EDB's yum repo .
Edit below file
/etc/yum.repos.d/edb.repo
Edit the above file and enable the [enterprisedb-tools] and the [enterprisedb-dependencies] entries. To enable a repository, change the value of the enabled parameter to 1 and replace the user name and password placeholders in the baseurl specification with your user name and the repository password.
[enterprisedb-tools]
name=EnterpriseDB Tools $releasever - $basearch
baseurl=https://<username>:<password>@yum.enterprisedb.com/tools-testing/redhat/rhel-$releasever-$basearch
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/ENTERPRISEDB-GPG-KEY
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Install EFM 3.2
yum install yum install edb-efm34
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Where
Failover Manager components are installed in the following locations:
Component
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Location
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Executables
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/usr/edb/efm-3.2/bin
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Libraries
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/usr/edb/efm-3.2/lib
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Cluster configuration files
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/etc/edb/efm-3.2
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Logs
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/var/log/efm-3.2
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Lock files
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/var/lock/efm-3.2
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Log rotation file
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/etc/logrotate.d/efm-3.2
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sudo configuration file
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/etc/sudoers.d/efm-32
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Binary to access VIP without sudo
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/usr/edb/efm-3.2/bin/secure
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Configure EDB EFM
1) Create dedicated user for EFM .
postgres=# create user efmtest with superuser ;
CREATE ROLE
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2) You must modify the pg_hba.conf file on the Master and Standby nodes, adding
entries that allow communication between the all of the nodes in the cluster.
host postgres efmtest 192.168.1.100/32 md5 ##Master
host postgres efmtest 192.168.1.102/32 md5 ##Slave
host postgres efmtest 192.168.1.103/32 md5 ##Witness
3) Encrypt your database user password .
Failover Manager requires you to encrypt your database password before including it in the cluster properties file.
/usr/edb/efm-3.2/bin/efm encrypt efm
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4) Make a configuration files .
After installation two sample files get created i.e
a) efm.property.in
b) efm.nodes.in
Make a copy of this file as
cp /etc/edb/efm-3.2/efm.properties.in /etc/edb/efm-3.2/efm.properties
cp /etc/edb/efm-3.2/efm.nodes.in /etc/edb/efm-3.2/efm.nodes
Where
efm is your cluster name ,If you want you can use another name .
5) I have changed some parameter in efm.properties which is as below .
db.user=efmtest
db.password.encrypted=e32f382eea7b5e2a4b413fa475e1e2c3
db.port=5432
db.database=postgres
db.service.owner=postgres
db.bin=/opt/PostgreSQL/10/bin
db.recovery.conf.dir=/opt/PostgreSQL/10/data
user.email=tushar.takate@enterprisedb.com
bind.address=192.168.0.192:7800
admin.port=7809
is.witness=false
stop.isolated.master=false
stop.failed.master=false
master.shutdown.as.failure=false
pingServerIp=8.8.8.8
pingServerCommand=/bin/ping -q -c3 -w5
auto.allow.hosts=true
stable.nodes.file=false
auto.failover=true
auto.reconfigure=true
promotable=true
recovery.check.period=2
auto.resume.period=5
virtualIp=192.168.0.108
virtualIp.interface=ens33
virtualIp.prefix=24
virtualIp.single=true
check.vip.before.promotion=true
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Note :
* bind.address
The bind.address property specifies the IP address and port number of the agent on the current node of the Failover Manager cluster.
* On witness node make sure it should be (is.witness=true) .
6) Make changes into efm.nodes file .
efm.nodes file contains a list of the current Failover Manager cluster members.
Add the addresses and ports of each node in the cluster to this file. One node will act as the membership coordinator; the list should include at least the membership coordinator's address:
efm.nodes entries on master .
efm.nodes entries on Slave .
efm.nodes entries on Witness .
After you start all the efm services .It will look like as below .
You can see now VIP is assigned with Master node .
Now i am testing switchover .
After performing the switchover cluster status will look like as below .And VIP will get assigned with new Master .
192.168.1.103:7800 192.168.1.102:7800
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efm.nodes entries on Slave .
192.168.1.100:7800 192.168.1.103:7800
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efm.nodes entries on Witness .
192.168.1.100:7800 192.168.1.102:7800
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7) Start the efm service on witness .
Generally keep sequence of EFM service start as below .
witness - master - slave .
systemctl start efm-3.2
## After service successfully start execute allow-node command .
[root@witness ~]# efm allow-node efm 192.168.1.100
allow-node signal sent to local agent.
[root@witness ~]# efm allow-node efm 192.168.1.102
allow-node signal sent to local agent.
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After witness service start it will looks like
[root@witness ~]# efm cluster-status efm
Cluster Status: efm
Agent Type Address Agent DB VIP
-----------------------------------------------------------------------
Witness 192.168.1.103 UP N/A 192.168.1.108
Allowed node host list:
192.168.1.103 192.168.1.100 192.168.1.102
Membership coordinator: 192.168.1.103
Standby priority host list:
(List is empty.)
Promote Status:
Did not find XLog location for any nodes.
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After you start all the efm services .It will look like as below .
You can see now VIP is assigned with Master node .
[root@master ~]# efm cluster-status efm
Cluster Status: efm
Agent Type Address Agent DB VIP
-----------------------------------------------------------------------
Master 192.168.1.100 UP UP 192.168.1.108*
Standby 192.168.1.102 UP UP 192.168.1.108
Witness 192.168.1.103 UP N/A 192.168.1.108
Allowed node host list:
192.168.1.103 192.168.1.100 192.168.1.102
Membership coordinator: 192.168.1.103
Standby priority host list:
192.168.1.102
Promote Status:
DB Type Address XLog Loc Info
--------------------------------------------------------------
Master 192.168.1.100 0/F5FCEE28
Standby 192.168.1.102 0/F5FCEE28
Standby database(s) in sync with master. It is safe to promote.
[root@master ~]#
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8 ) Performing Switchover/failover to make old Master as a slave and old salve as a new master .
You can invoke efm promote on any node of a Failover Manager cluster to start a manual promotion of a Standby database to Master database.
- Command to perform manual failover .
efm promote efm
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- Command to perform manual switchover .
efm promote efm -switchover
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Now i am testing switchover .
[root@slave ~]# efm promote efm -switchover
Promote/switchover command accepted by local agent. Proceeding with promotion and will reconfigure original master. Run the 'cluster-status' command for information about the new cluster state.
[root@slave ~]#
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After performing the switchover cluster status will look like as below .And VIP will get assigned with new Master .
[root@slave ~]# efm cluster-status efm
Cluster Status: efm
Agent Type Address Agent DB VIP
-----------------------------------------------------------------------
Standby 192.168.1.100 UP UP 192.168.1.108
Master 192.168.1.102 UP UP 192.168.1.108*
Witness 192.168.1.103 UP N/A 192.168.1.108
Allowed node host list:
192.168.1.103 192.168.1.100 192.168.1.102
Membership coordinator: 192.168.1.103
Standby priority host list:
192.168.1.100
Promote Status:
DB Type Address XLog Loc Info
--------------------------------------------------------------
Master 192.168.1.102 0/F60001A8
Standby 192.168.1.100 0/F60001A8
Standby database(s) in sync with master. It is safe to promote.
[root@slave ~]#
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For more information and different switches/commands of EFM ,Please visit EDB's website .
You can get EDB's official document from - Link
