操作系统：CentOS 7.3

PostgreSQL：9.6

/etc/hosts:

192.168.0.1  node1
192.168.0.2  node2
192.168.0.3  # VIP
192.168.0.4  # VIP

按照本指南进行 PostgreSQL 复制：

https://www.digitalocean.com/community/tutorials/how-to-set-up-master-slave-replication-on-postgresql-on-an-ubuntu-12-04-vps

我用这种方式做第一个初始数据库副本：

psql -c "select pg_start_backup('initial_backup');"
rsync -cva --inplace --exclude=*pg_xlog* ~postgres/9.6/data/ 192.168.0.2:~postgres/9.6/data/
psql -c "select pg_stop_backup();"

然后编辑到正确的 IP pg_hba.conf。postgresql.conf然后创建一个recovery.conf文件插入这个：

standby_mode = 'on'
primary_conninfo = 'host=192.168.0.1 port=5432 user=rep password=password'
restore_command = 'cp /var/lib/pgsql/9.6/pg_archive/%f %p'
recovery_target_timeline = 'latest'

遵循官方指南：

https://wiki.clusterlabs.org/wiki/PgSQL_Replicated_Cluster

设置config.pcs：

pcs cluster cib pgsql_cfg

pcs -f pgsql_cfg property set no-quorum-policy="ignore"
pcs -f pgsql_cfg property set stonith-enabled="false"
pcs -f pgsql_cfg resource defaults resource-stickiness="INFINITY"
pcs -f pgsql_cfg resource defaults migration-threshold="1"

pcs -f pgsql_cfg resource create vip-master IPaddr2 \
   ip="192.168.0.3" \
   nic="ens192" \
   cidr_netmask="24" \
   op start   timeout="60s" interval="0s"  on-fail="restart" \
   op monitor timeout="60s" interval="10s" on-fail="restart" \
   op stop    timeout="60s" interval="0s"  on-fail="block"

pcs -f pgsql_cfg resource create vip-rep IPaddr2 \
   ip="192.168.0.4" \
   nic="ens192" \
   cidr_netmask="24" \
   meta migration-threshold="0" \
   op start   timeout="60s" interval="0s"  on-fail="stop" \
   op monitor timeout="60s" interval="10s" on-fail="restart" \
   op stop    timeout="60s" interval="0s"  on-fail="ignore"

pcs -f pgsql_cfg resource create pgsql pgsql \
   pgctl="/usr/pgsql-9.6/bin/pg_ctl" \
   psql="/usr/pgsql-9.6/bin/psql" \
   pgdata="/var/lib/pgsql/9.6/data/" \
   rep_mode="sync" \
   node_list="node1 node2" \
   restore_command="cp /var/lib/pgsql/9.6/pg_archive/%f %p" \
   primary_conninfo_opt="keepalives_idle=60 keepalives_interval=5 keepalives_count=5" \
   master_ip="192.168.0.4" \
   restart_on_promote='true' \
   op start   timeout="60s" interval="0s"  on-fail="restart" \
   op monitor timeout="60s" interval="4s" on-fail="restart" \
   op monitor timeout="60s" interval="3s"  on-fail="restart" role="Master" \
   op promote timeout="60s" interval="0s"  on-fail="restart" \
   op demote  timeout="60s" interval="0s"  on-fail="stop" \
   op stop    timeout="60s" interval="0s"  on-fail="block" \
   op notify  timeout="60s" interval="0s"

pcs -f pgsql_cfg resource master msPostgresql pgsql \
   master-max=1 master-node-max=1 clone-max=2 clone-node-max=1 notify=true

pcs -f pgsql_cfg resource group add master-group vip-master vip-rep

pcs -f pgsql_cfg constraint colocation add master-group with Master msPostgresql INFINITY
pcs -f pgsql_cfg constraint order promote msPostgresql then start master-group symmetrical=false score=INFINITY
pcs -f pgsql_cfg constraint order demote  msPostgresql then stop  master-group symmetrical=false score=0

pcs cluster cib-push pgsql_cfg

加载配置

sh config.pcs

再次查看状态：

crm_mon -Afr -1

结果：

Stack: corosync
Current DC: node1 (version 1.1.15-11.el7_3.5-e174ec8) - partition with quorum
Last updated: Thu Jul 27 07:29:35 2017          Last change: Thu Jul 27 07:13:11 2017 by hacluster via crmd on node1

2 nodes and 4 resources configured

Online: [ node1 node2 ]

Full list of resources:

 Master/Slave Set: msPostgresql [pgsql]
     Masters: [ node2 ]
     Slaves: [ node1 ]
 Resource Group: master-group
     vip-master (ocf::heartbeat:IPaddr2):       Started node2
     vip-rep    (ocf::heartbeat:IPaddr2):       Started node2

Node Attributes:
* Node node1:
    + master-pgsql                      : -INFINITY
    + pgsql-data-status                 : DISCONNECT
    + pgsql-status                      : HS:alone
* Node node2:
    + master-pgsql                      : 1000
    + pgsql-data-status                 : LATEST
    + pgsql-master-baseline             : 0000000011000140
    + pgsql-status                      : PRI

Migration Summary:
* Node node1:
* Node node2:

为什么node1无法连接。

此时检查recovery.conf两个节点上的文件：

节点 1：

standby_mode = 'on'
primary_conninfo = 'host=192.168.0.4 port=5432 user=postgres application_name=node1 keepalives_idle=60 keepalives_interval=5 keepalives_count=5'
restore_command = 'cp /var/lib/pgsql/9.6/pg_archive/%f %p'
recovery_target_timeline = 'latest'

节点 2：

（无效的）

按照本指南执行 PostgreSQL 自动故障转移：

https://dalibo.github.io/PAF/Quick_Start-CentOS-7.html

在这一步：

pcs -f cluster1.xml stonith create fence_vm_srv1 fence_virsh pcmk_host_check="static-list" pcmk_host_list="srv1" ipaddr="192.168.122.1" login="<username>" port="srv1-c7" action="off" identity_file="/root/.ssh/id_rsa"
pcs -f cluster1.xml stonith create fence_vm_srv2 fence_virsh pcmk_host_check="static-list" pcmk_host_list="srv2" ipaddr="192.168.122.1" login="<username>" port="srv2-c7" action="off" identity_file="/root/.ssh/id_rsa"
pcs -f cluster1.xml stonith create fence_vm_srv3 fence_virsh pcmk_host_check="static-list" pcmk_host_list="srv3" ipaddr="192.168.122.1" login="<username>" port="srv3-c7" action="off" identity_file="/root/.ssh/id_rsa"
pcs -f cluster1.xml constraint location fence_vm_srv1 avoids srv1=INFINITY
pcs -f cluster1.xml constraint location fence_vm_srv2 avoids srv2=INFINITY
pcs -f cluster1.xml constraint location fence_vm_srv3 avoids srv3=INFINITY

我编辑的内容：

pcs -f cluster1.xml stonith create fence_vm_node1 fence_virsh pcmk_host_check="static-list" pcmk_host_list="node1" ipaddr="192.168.33.1" login="root" port="5432" action="off" identity_file="/root/.ssh/id_rsa"
pcs -f cluster1.xml stonith create fence_vm_node2 fence_virsh pcmk_host_check="static-list" pcmk_host_list="node2" ipaddr="192.168.33.1" login="root" port="5432" action="off" identity_file="/root/.ssh/id_rsa"
pcs -f cluster1.xml constraint location fence_vm_node1 avoids node1=INFINITY
pcs -f cluster1.xml constraint location fence_vm_node2 avoids node2=INFINITY

出现错误：

[root@node1 ~]# pcs -f cluster1.xml stonith create fence_vm_node1 fence_virsh pcmk_host_check="static-list" pcmk_host_list="node1" ipaddr="192.168.33.1" login="root" port="5432" action="off" identity_file="/root/.ssh/id_rsa"
Error: Agent 'fence_virsh' not found, use --force to override
[root@node1 ~]# pcs -f cluster1.xml stonith create fence_vm_node2 fence_virsh pcmk_host_check="static-list" pcmk_host_list="node2" ipaddr="192.168.33.1" login="root" port="5432" action="off" identity_file="/root/.ssh/id_rsa"
Error: Agent 'fence_virsh' not found, use --force to override
[root@node1 ~]# pcs -f cluster1.xml constraint location fence_vm_node1 avoids node1=INFINITY
Error: Resource 'fence_vm_node1' does not exist
[root@node1 ~]# pcs -f cluster1.xml constraint location fence_vm_node2 avoids node2=INFINITY
Error: Resource 'fence_vm_node2' does not exist

没有这个 IP: 192.168.33.1，但存在192.168.33.111。

我认为portPostgreSQL 的端口，将其更改为5432. 也许不是那个意思。那么正确的含义是什么？

哪里错了？

从本指南中我们知道DRBD可用于 PostgreSQL 主动/被动设置：

https://www.howtoforge.com/how-to-set-up-an-active-passive-postgresql-cluster-with-pacemaker-corosync-and-drbd-centos-5.5-p4

它用于/dev/drbd0挂载 PostgreSQL 数据路径/var/lib/psql：

mount -t ext3 /dev/drbd0 /var/lib/pgsql

那么是否可以使用这种方式挂载一个MongoDB数据路径，该路径在哪里？（Maybe this on CentOS 7.3: /var/lib/mongo）

如果使用这种方式，多个节点将使用同步的相同文件数据而不是主从复制。也许这就是所谓的主-主复制。好吗？

按照本指南进行 PostgreSQL 复制：

https://www.digitalocean.com/community/tutorials/how-to-set-up-master-slave-replication-on-postgresql-on-an-ubuntu-12-04-vps

我没有这样做：

psql -c "select pg_start_backup('initial_backup');"
rsync -cva --inplace --exclude=*pg_xlog* /var/lib/postgresql/9.1/main/ slave_IP_address:/var/lib/postgresql/9.1/main/
psql -c "select pg_stop_backup();"

在我配置了主节点和从节点之后，测试在主节点上创建一个表，没有发现新数据已同步到从节点。

从本指南中，我看到需要archive_command在文件中添加一个配置recovery.conf：

https://www.server-world.info/en/note?os=CentOS_7&p=postgresql&f=3

archive_command = 'cp %p /var/lib/pgsql/archive/%f'

但 PostgreSQL 9.6 可能不支持该功能。那么如何自动同步呢？

添加

这很有帮助：

https://dalibo.github.io/PAF/Quick_Start-CentOS-7.html

使用以下方式安装 PostgreSQL：

sudo yum install postgresql-server postgresql-contrib

PostgreSQL 版本：9.2.18

启动服务时：

sudo service postgresql start

得到错误：

Redirecting to /bin/systemctl start  postgresql.service
Job for postgresql.service failed because the control process exited with error code. See "systemctl status postgresql.service" and "journalctl -xe" for details.

journalctl -xe细节：

-- Unit postgresql.service has failed.
--
-- The result is failed.
 7月 19 04:17:04 node2 systemd[1]: Unit postgresql.service entered failed state.
 7月 19 04:17:04 node2 systemd[1]: postgresql.service failed.
 7月 19 04:17:04 node2 polkitd[19772]: Unregistered Authentication Agent for unix-process:27133:53830492 (system bus name :1.405, object path /org/freedesktop/PolicyKit1/AuthenticationA
 7月 19 04:19:33 node2 polkitd[19772]: Registered Authentication Agent for unix-process:27165:53845472 (system bus name :1.406 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object pat
 7月 19 04:19:33 node2 systemd[1]: Starting PostgreSQL database server...
-- Subject: Unit postgresql.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit postgresql.service has begun starting up.
 7月 19 04:19:34 node2 pg_ctl[27187]: pg_ctl: could not start server
 7月 19 04:19:34 node2 pg_ctl[27187]: Examine the log output.
 7月 19 04:19:34 node2 systemd[1]: postgresql.service: control process exited, code=exited status=1
 7月 19 04:19:34 node2 systemd[1]: Failed to start PostgreSQL database server.
-- Subject: Unit postgresql.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit postgresql.service has failed.
--
-- The result is failed.
 7月 19 04:19:34 node2 systemd[1]: Unit postgresql.service entered failed state.
 7月 19 04:19:34 node2 systemd[1]: postgresql.service failed.
 7月 19 04:19:34 node2 polkitd[19772]: Unregistered Authentication Agent for unix-process:27165:53845472 (system bus name :1.406, object path /org/freedesktop/PolicyKit1/AuthenticationA
lines 2850-2910/2910 (END)

运行systemctl status PostgreSQL.service，得到以下信息：

● postgresql.service - PostgreSQL database server
   Loaded: loaded (/usr/lib/systemd/system/postgresql.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Wed 2017-07-19 04:30:26 EDT; 42min ago
  Process: 27285 ExecStart=/usr/bin/pg_ctl start -D ${PGDATA} -s -o -p ${PGPORT} -w -t 300 (code=exited, status=1/FAILURE)
  Process: 27280 ExecStartPre=/usr/bin/postgresql-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
 Main PID: 26640 (code=exited, status=0/SUCCESS)

在 CentOS 7 上。

MongoDB 版本：3.2.15

有两个节点：

• 节点1
• 节点2

节点1

/etc/hosts

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4 node1
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.0.100              node1
192.168.0.101              node2

# mongod.conf

# for documentation of all options, see:
#   http://docs.mongodb.org/manual/reference/configuration-options/

# where to write logging data.
systemLog:
  destination: file
  logAppend: true
  path: /var/log/mongodb/mongod.log

# Where and how to store data.
storage:
  dbPath: /mongo-metadata
  journal:
    enabled: true
#  engine:
#  mmapv1:
#  wiredTiger:

# how the process runs
processManagement:
  fork: true  # fork and run in background
  pidFilePath: /var/run/mongodb/mongod.pid  # location of pidfile

# network interfaces
net:
  port: 27017
  bindIp: 127.0.0.1 192.168.0.100  # Listen to local interface only, comment to listen on all interfaces.


security:
  keyFile: /root/keyfile

#operationProfiling:

replication:
  replSetName: rs0

#sharding:

## Enterprise-Only Options

#auditLog:

#snmp:

节点2

/etc/hosts

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4 node2
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.0.100              node1
192.168.0.101              node2

/etc/mongod.conf

# mongod.conf

# for documentation of all options, see:
#   http://docs.mongodb.org/manual/reference/configuration-options/

# where to write logging data.
systemLog:
  destination: file
  logAppend: true
  path: /var/log/mongodb/mongod.log

# Where and how to store data.
storage:
  dbPath: /mongo-metadata
  journal:
    enabled: true
#  engine:
#  mmapv1:
#  wiredTiger:

# how the process runs
processManagement:
  fork: true  # fork and run in background
  pidFilePath: /var/run/mongodb/mongod.pid  # location of pidfile

# network interfaces
net:
  port: 27017
  bindIp: 127.0.0.1 192.168.0.101  # Listen to local interface only, comment to listen on all interfaces.


security:
  keyFile: /root/keyfile

#operationProfiling:

replication:
  replSetName: rs0

#sharding:

## Enterprise-Only Options

#auditLog:

#snmp:

在 node1 上运行 mongo 命令

mongo
rs.initiate()
use admin
db.createUser(...)
db.auth('admin', '...')
rs.add('node2')

导致错误：

{
    "ok" : 0,
    "errmsg" : "Quorum check failed because not enough voting nodes responded; required 2 but only the following 1 voting nodes responded: node1:27017; the following nodes did not respond affirmatively: node2:27017 failed with No route to host",
    "code" : 74
}

它不能从node1连接到node2吗？有没有关于如何做 mongodb 复制集的官方指南？

使用 CentOS 7。

MongoDB 版本：3.2.15

主机名：node1

制作目录：

mkdir /mongo-metadata

/etc/mongod.conf

# mongod.conf

# for documentation of all options, see:
#   http://docs.mongodb.org/manual/reference/configuration-options/

# where to write logging data.
systemLog:
  destination: file
  logAppend: true
  path: /var/log/mongodb/mongod.log

# Where and how to store data.
storage:
  dbPath: /mongo-metadata
  journal:
    enabled: true
#  engine:
#  mmapv1:
#  wiredTiger:

# how the process runs
processManagement:
  fork: true  # fork and run in background
  pidFilePath: /var/run/mongodb/mongod.pid  # location of pidfile

# network interfaces
net:
  port: 27017
  bindIp: 127.0.0.1  # Listen to local interface only, comment to listen on all interfaces.


#security:

#operationProfiling:

replication:
  replSetName: rs0

#sharding:

## Enterprise-Only Options

#auditLog:

#snmp:

启动复制成员：

mongod --config /etc/mongod.conf

运行mongo：

mongo
# try
rs.initiate()    
{
        "info2" : "no configuration specified. Using a default configuration for the set",
        "me" : "node1:27017",
        "ok" : 0,
        "errmsg" : "No host described in new configuration 1 for replica set rs0 maps to this node",
        "code" : 93
}

# try
config = {
    _id : "rs0",
     members : [
         {_id : 0, host : "node1:27017"},
         {_id : 1, host : "node2:27017"},
     ]
}
rs.initiate(config)
{
    "ok" : 0,
    "errmsg" : "No host described in new configuration 1 for replica set rs0 maps to this node",
    "code" : 93
}

参考：

https://docs.mongodb.com/manual/reference/command/replSetInitiate/

那么是什么原因呢？它无法识别主机名？