VMware Cloud Director 维护节点之间的同步流式传输复制。如果备用节点变得无法访问,则必须确定原因并解决问题。

问题

VMware Cloud Director 设备管理 UI 显示集群运行状况为 DEGRADED,其中一个备用节点的状态为 unreachable

/nodes API 返回以下信息:localClusterHealthDEGRADED,节点的 statusunreachablenodeHealthUNHEALTHY

例如, /nodes API 可能会返回以下节点信息。
{
    "localClusterFailover": "MANUAL",
    "localClusterHealth": "DEGRADED",
    "localClusterState": [
        {
            "connectionString": "host=primary_host_IP user=repmgr dbname=repmgr connect_timeout=2",
            "failover": {
                "details": "failover = manual",
                "mode": "MANUAL",
                "repmgrd": {
                    "details": "On node primary_node_ID (primary_host_name): repmgrd = not applicable",
                    "status": "NOT APPLICABLE"
                }
            },
            "id": primary_node_ID,
            "location": "default",
            "name": "primary_host_name",
            "nodeHealth": "HEALTHY",
            "nodeRole": "PRIMARY",
            "role": "primary",
            "status": "* running",
            "upstream": ""
        },
        {
            "connectionString": "host=unreachable_standby_host_IP user=repmgr dbname=repmgr connect_timeout=2",
            "failover": {
                "details": "failover state unknown - unable to ssh to failed or unreachable node",
                "mode": "UNKNOWN",
                "repmgrd": {
                    "details": "On node unreachable_standby_node_ID (unreachable_standby_host_name): repmgrd = n/a",
                    "status": "UNKNOWN"
                }
            },
            "id": unreachable_standby_node_ID,
            "location": "default",
            "name": "unreachable_standby_host_name",
            "nodeHealth": "UNHEALTHY",
            "nodeRole": "STANDBY",
            "role": "standby",
            "status": "? unreachable",
            "upstream": "primary_host_name"
        },
        {
            "connectionString": "host=running_standby_host_IP user=repmgr dbname=repmgr connect_timeout=2",
            "failover": {
                "details": "failover = manual",
                "mode": "MANUAL",
                "repmgrd": {
                    "details": "On node running_standby_node_ID (running_standby_host_IP): repmgrd = not applicable",
                    "status": "NOT APPLICABLE"
                }
            },
            "id": running_standby_node_ID,
            "location": "default",
            "name": "running_standby_host_name",
            "nodeHealth": "HEALTHY",
            "nodeRole": "STANDBY",
            "role": "standby",
            "status": "running",
            "upstream": "primary_host_name"
        }
    ],
    "warnings": [
        "unable to connect to node \"unreachable_standby_host_name\" (ID: unreachable_standby_node_ID)",
        "node \"unreachable_standby_host_name\" (ID: unreachable_standby_node_ID) is registered as an active standby but is unreachable"
    ]
}

原因

为确保数据完整性,PostgreSQL 数据库使用预写式日志记录 (WAL)。主节点不断地将 WAL 流式传输到活动备用节点,以便进行复制和恢复。备用节点在接收到 WAL 后对其进行处理。如果备用节点无法访问,则将停止接收 WAL,并且无法作为候选节点提升为新的主节点。

解决方案

  • 验证无法访问的备用节点的虚拟机是否正在运行。
  • 验证备用节点的网络连接是否正常工作。
  • 验证是否存在可能阻止备用节点与其他节点通信的 SSH 问题。
  • 验证备用节点上的 vpostgres 服务是否正在运行。

下一步做什么

要验证是否存在网络或 SSH 问题,请参见 检查数据库高可用性群集的连接状态