Question

我有pgpool的这个配置：“Host-1”master和“Host-2”slave，如果“Host-1”关闭，pgpool正确地将“Host-2”提升为master;但是如果“Host-1”返回，pgpool不知道这一点，如果“Host-2”出现故障，pgpool不会将“Host-1”提升为主节点，即使“Host-1”是线上。我启用了health_check，但它似乎完全无用，因为“Host-1”的状态（在它变为up之后）总是3 =“Node is down”。

这是事件期间命令“show pool_nodes”的输出：

- ＆GT;最初情况：“Host-1”UP（主站），“Host-2”UP（从站）

 node_id | hostname | port | status | lb_weight |  role
---------+----------+------+--------+-----------+--------
 0       | Host-1    | 5432 | 2      | nan       | master
 1       | Host-2    | 5432 | 1      | nan       | slave

- ＆GT;节点0关闭：“Host-1”DOWN，“Host-2”UP

 node_id | hostname | port | status | lb_weight |  role
---------+----------+------+--------+-----------+--------
 0       | Host-1    | 5432 | 3      | nan       | slave
 1       | Host-2    | 5432 | 2      | nan       | master

- ＆GT;节点0返回：“Host-1”UP，“Host-2”UP

 node_id | hostname | port | status | lb_weight |  role
---------+----------+------+--------+-----------+--------
 0       | Host-1    | 5432 | 3      | nan       | slave
 1       | Host-2    | 5432 | 2      | nan       | master

请注意，“Host-1”的状态为3表示“Node is down”

- ＆GT;节点1出现故障：“Host-1”UP，“Host-2”DOWN：此时我无法连接到db，即使节点0已启动并运行！

我需要做什么才能允许pgpool再次提升节点0的主控权？如果有用，这些是我的pgpool.conf的“后端连接设置”和“健康检查”部分：

# - Backend Connection Settings -

backend_hostname0 = 'Host-1'
                                   # Host name or IP address to connect to for backend 0
backend_port0 = 5432
                                   # Port number for backend 0
#backend_weight0 = 1
                                   # Weight for backend 0 (only in load balancing mode)
#backend_data_directory0 = '/data'
                                   # Data directory for backend 0
backend_flag0 = 'ALLOW_TO_FAILOVER'
                                   # Controls various backend behavior
                                   # ALLOW_TO_FAILOVER or DISALLOW_TO_FAILOVER

backend_hostname1 = 'Host-2'
                                   # Host name or IP address to connect to for backend 0
backend_port1 = 5432
                                   # Port number for backend 0
#backend_weight1 = 1
                                   # Weight for backend 0 (only in load balancing mode)
#backend_data_directory1 = '/data'
                                   # Data directory for backend 0
backend_flag1 = 'ALLOW_TO_FAILOVER'
                                   # Controls various backend behavior
                                   # ALLOW_TO_FAILOVER or DISALLOW_TO_FAILOVER

#------------------------------------------------------------------------------
# HEALTH CHECK
#------------------------------------------------------------------------------

health_check_period = 10
                                   # Health check period
                                   # Disabled (0) by default
health_check_timeout = 20
                                   # Health check timeout
                                   # 0 means no timeout
health_check_user = 'admin'
                                   # Health check user
health_check_password = '12345'
                                   # Password for health check user
health_check_max_retries = 10
                                   # Maximum number of times to retry a failed health check before giving up.
health_check_retry_delay = 1
                                   # Amount of time to wait (in seconds) between retries.

Answer 1

一旦您的从属节点启动并且复制正在运行，您需要将节点重新连接到pgpool。

$ pcp_attach_node 10 pgpool_host 9898 admin _pcp_passwd_ 0

最后一个参数是节点ID，对于你的情况，它是0。

请参阅http://www.pgpool.net/docs/latest/pgpool-en.html#pcp_attach_node详细信息。

Answer 2

在升级之前，您必须将 up 从属节点。这意味着，在您的情况下，使用Slony完全故障转移并重建前Master作为新Slave。

基本问题是写入新主服务器的写入必须先复制到旧主服务器，然后才能进行故障恢复。这首先是一个Slony问题。在验证Slony正在运行并且所有内容都已复制之后，您可以对pgpool端进行故障排除，但直到那时（然后您可能需要将其重新连接到PGPool）。在主/从模式下使用PGPool时，PGPool是您正在使用的任何其他复制系统的辅助。

pgpool-II：是否有可能促使节点多次掌握？

2 个答案: