+**postgresql.conf.master** : A config file for postgres master node.
+
+**postgresql.conf.slave** : A config file for postgres slave node.
+
+**recovery.conf** : A config file used by postgres slave for streaming replication process.
+
+**failover.sh** : This script will be executed automatically when a pgpool's backend node (postgres node) fall down. It'll switch the standby node (slave) to master (new master).
+
+**online-recovery.sh** : This is the bash script which you'll execute manually in order to :
+* Reboot, sync and reattach slave node to pgpool if it fails.
+* Setup new master and new slave, sync and reattach them to pgpool if current master fails.
+This script will invoque remotely the script streaming-replication.sh (in the new slave node) to start the [online recovery process](http://www.postgresql.org/docs/8.1/static/backup-online.html) within the standby node.
+PS : When a node (master or slave) fails, pgpool still running and DBs remain available. Otherwise, pgpool will detach this node for data consistancy reasons.
+
+**streaming-replication.sh** : This script can be executed manually to synchronize a slave node with a given master node (master name/ip must be passed as argument to streaming-replication.sh). Otherwise, this same script is triggred be online-recovery.sh via ssh during failback process.
+
+The installation steps are simple. You just need to copy provided bash scripts and config files as follow :
+
+In pgpool node:
+* Copy pgpool.conf to /etc/pgpool2/. This is an optional operation and in this case you have to edit the default pgpool.conf file in order to looks like the config file we provided.
+* Copy failover.sh into /usr/local/bin/ and online-recovery.sh to your home or another directory that will be easily accessible.
+
+In the master and slave postgres nodes:
+* Copy streaming-replication.sh script into /var/lib/postgresql/ (postgres homedir).
+* Copy postgresql.conf.master and postgresql.conf.slave files to /etc/postgresql/9.1/main/.
+* Finally copy recovery.conf into /var/lib/postgresql/9.1/main/.
+
+PS : All similar old files must be backed up to be able to rollback in case of risk (e.g: cp -p /etc/pgpool2/pgpool.conf /etc/pgpool2/pgpool.conf.backup).
+Make sure that :
+- All scripts are executable and owned by the proper users.
+- /var/lib/postgresql/9.1/archive directory is created (used to archive WAL files). This directory must be owned by postgres user !
+
+Not enough ! It remains only the configuration steps and we'll be done :) To do, just follow these steps :
+
+* First of all make sure you have created a postgres user in pgpool node with SSH access to all Postgres nodes. All cluster's nodes have to be able to ssh each other. You can put "config" file with "StrictHostKeyChecking=no" option under .ssh/ directory of postgres user. This is a best practice (essencially when automating a bunch of operations) that allows postgres to ssh remote machine for the first time without prompting and validating Yes/No authorization question.
+
+* In Pgpool node set up pgpool.conf file for instance the parameters: ::
+
+ # Controls various backend behavior for instance master and slave(s).
+ backend_hostname0='master.foo.bar'
+ backend_port0 = 5432
+ backend_weight0 = 1
+ backend_data_directory0 = '/var/lib/postgres/9.1/main/'
+ backend_flag0 = 'ALLOW_TO_FAILOVER'
+ backend_hostname1='slave.foo.bar'
+ backend_port1 = 5432
+ backend_weight1 = 1
+ backend_data_directory1 = '/var/lib/postgres/9.1/main/'
+ backend_flag1 = 'ALLOW_TO_FAILOVER'
+ # Pool size
+ num_init_children = 32
+ max_pool = 4
+ # Master/Slave and load balancing (replication mode must be off)
+ load_balance_mode = on
+ master_slave_mode = on
+ master_slave_sub_mode = 'stream'
+ #Health check (must be set up to detecte postgres server status up/down)
+ health_check_period = 30
+ health_check_user = 'postgres'
+ health_check_password = 'postgrespass'
+ # Failover command
+ failover_command = '/path/to/failover.sh %d %H %P /tmp/trigger_file'
+
+* In failover.sh script, specify the proper ssh private key to postgres user to access new master node via SSH. ::
+
+ ssh -i /var/lib/postgresql/.ssh/id_rsa postgres@$new_master "touch $trigger_file"
+
+* Idem for online-recovery.sh you have juste to change if needed the postgres's private key, the rest of params is set automatically when the script runs. Magic hein ! :)
+
+* Change the primary_conninfo access parameters (to master) in recovery.conf file in slave side : ::
+
+ primary_conninfo = 'host=master-or-slave.foo.bar port=5432 user=postgres password=nopass'
+
+* Rename recovery.conf to recovery.done in master side.
+
+* Setup postgres master node (after backup of postgresql.conf) : ::
+
+ cp -p postgresql.conf.master postgresql.conf
+ /etc/init.d/postgresql restart
+
+* Setup postgres slave node (after backup of postgresql.conf) : ::
+
+ cp -p postgresql.conf.slave postgresql.conf
+
+* Start first slave synchronisation with master by executing streaming-replication.sh as postgres user : ::
+
+ su postgres
+ cd ~
+ ./streaming-replication.sh master.foo.bar
+
+* Restart pgpool : ::
+
+ /etc/init.d/pgpool2 restart
+
+At his stage slave node is connected to master and both of them are connected to pgpool. If the master fails down, pgpool detach it from the pool and perform failover process (slave become master) automatically.
projects / pgpool-online-recovery / commitdiff