一、集群复制状态检查
1、SHOW GLOBAL STATUS LIKE ‘wsrep_%‘;
+------------------------------+-------------------------------------------------------------+
| Variable_name | Value |
+------------------------------+-------------------------------------------------------------+
| wsrep_local_state_uuid | 9f6a992a-7dd9-11e5-9f85-f760745ffb39 |
| wsrep_protocol_version | 7 |
| wsrep_last_committed | 53 |
| wsrep_replicated | 6 |
| wsrep_replicated_bytes | 1368 |
| wsrep_repl_keys | 9 |
| wsrep_repl_keys_bytes | 210 |
| wsrep_repl_data_bytes | 774 |
| wsrep_repl_other_bytes | 0 |
| wsrep_received | 37 |
| wsrep_received_bytes | 23347 |
| wsrep_local_commits | 0 |
| wsrep_local_cert_failures | 0 |
| wsrep_local_replays | 0 |
| wsrep_local_send_queue | 0 |
| wsrep_local_send_queue_max | 2 |
| wsrep_local_send_queue_min | 0 |
| wsrep_local_send_queue_avg | 0.125000 |
| wsrep_local_recv_queue | 0 |
| wsrep_local_recv_queue_max | 2 |
| wsrep_local_recv_queue_min | 0 |
| wsrep_local_recv_queue_avg | 0.027027 |
| wsrep_local_cached_downto | 14 |
| wsrep_flow_control_paused_ns | 0 |
| wsrep_flow_control_paused | 0.000000 |
| wsrep_flow_control_sent | 0 |
| wsrep_flow_control_recv | 0 |
| wsrep_cert_deps_distance | 1.000000 |
| wsrep_apply_oooe | 0.100000 |
| wsrep_apply_oool | 0.000000 |
| wsrep_apply_window | 1.250000 |
| wsrep_commit_oooe | 0.000000 |
| wsrep_commit_oool | 0.000000 |
| wsrep_commit_window | 1.250000 |
| wsrep_local_state | 4 |
| wsrep_local_state_comment | Synced |
| wsrep_cert_index_size | 10 |
| wsrep_cert_bucket_count | 22 |
| wsrep_gcache_pool_size | 27144 |
| wsrep_causal_reads | 0 |
| wsrep_cert_interval | 0.325000 |
| wsrep_incoming_addresses | |
| wsrep_evs_delayed | |
| wsrep_evs_evict_list | |
| wsrep_evs_repl_latency | 0/0/0/0/0 |
| wsrep_evs_state | OPERATIONAL |
| wsrep_gcomm_uuid | 5e28860a-829e-11e5-9c06-665d7fe4003d |
| wsrep_cluster_conf_id | 3 |
| wsrep_cluster_size | 3 |
| wsrep_cluster_state_uuid | 9f6a992a-7dd9-11e5-9f85-f760745ffb39 |
| wsrep_cluster_status | Primary |
| wsrep_connected | ON |
| wsrep_local_bf_aborts | 0 |
| wsrep_local_index | 1 |
| wsrep_provider_name | Galera |
| wsrep_provider_vendor | Codership Oy <[email protected]> |
| wsrep_provider_version | 3.12(rXXXX) |
| wsrep_ready | ON |
+------------------------------+-------------------------------------------------------------+
wsrep_notify_cmd.sh——监控状态的变化。使用方法参见http://galeracluster.com/documentation-webpages/notificationcmd.html
2、wsrep_cluster_state_uuid显示了cluster的state UUID,由此可看出节点是否还是集群的一员
SHOW GLOBAL STATUS LIKE ‘wsrep_cluster_state_uuid‘
集群内每个节点的value都应该是一样的，否则说明该节点不在集群中了
+--------------------------+--------------------------------------+
| Variable_name | Value |
+--------------------------+--------------------------------------+
| wsrep_cluster_state_uuid | 9f6a992a-7dd9-11e5-9f85-f760745ffb39 |
+--------------------------+--------------------------------------+
3、wsrep_cluster_conf_id显示了整个集群的变化次数。所有节点都应相同，否则说明某个节点与集群断开了
4、wsrep_cluster_size显示了集群中节点的个数
5、wsrep_cluster_status显示集群里节点的主状态。标准返回primary。如返回non-Primary或其他值说明是多个节点改变导致的节点丢失或者脑裂。如果所有节点都返回不是Primary，则要重设quorum。具体参见http://galeracluster.com/documentation-webpages/quorumreset.html如果返回都正常，说明复制机制在每个节点都能正常工作，下一步该检查每个节点的状态确保他们都能收到write-set
show global status like ‘wsrep_cluster_status‘;
+----------------------+---------+
| Variable_name | Value |
+----------------------+---------+
| wsrep_cluster_status | Primary |
+----------------------+---------+
二、检查节点状态
节点状态显示了集群中的节点接受和更新write-set状态，以及可能阻止复制的一些问题
1、wsrep_ready显示了节点是否可以接受queries。ON表示正常，如果是OFF几乎所有的query都会报错，报错信息提示“ERROR 1047 (08501) Unknown Command”
SHOW GLOBAL STATUS LIKE ‘wsrep_ready‘;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wsrep_ready | ON |
+---------------+-------+
2、SHOW GLOBAL STATUS LIKE ‘wsrep_connected’显示该节点是否与其他节点有网络连接。（实验得知，当把某节点的网卡down掉之后，该值仍为on。说明网络还在）丢失连接的问题可能在于配置wsrep_cluster_address或wsrep_cluster_name的错误
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| wsrep_connected | ON |
+-----------------+-------+
3、wsrep_local_state_comment 以人能读懂的方式显示节点的状态，正常的返回值是Joining, Waiting on SST, Joined, Synced or Donor，返回Initialized说明已不在正常工作状态
+---------------------------+--------+
| Variable_name | Value |
+---------------------------+--------+
| wsrep_local_state_comment | Synced |
+---------------------------+--------+
三、查看复制的健康状态
通过Flow Control的反馈机制来管理复制进程。当本地收到的write-set超过某一阀值时，该节点会启动flow control来暂停复制直到它赶上进度。监控本地收到的请求和flow control，有如下几个参数：
1、wsrep_local_recv_queue_avg——平均请求队列长度。当返回值大于0时，说明apply write-sets比收write-set慢，有等待。堆积太多可能导致启动flow control
+----------------------------+----------+
| Variable_name | Value |
+----------------------------+----------+
| wsrep_local_recv_queue_avg | 0.027027 |
+----------------------------+----------+
wsrep_local_recv_queue_max 和 wsrep_local_recv_queue_min可以看队列设置的最大最小值
2、wsrep_flow_control_paused 显示了自从上次查询之后，节点由于flow control而暂停的时间占整个查询间隔时间比。总体反映节点落后集群的状况。如果返回值为1，说明自上次查询之后，节点一直在暂停状态。如果发现某节点频繁落后集群，则应该调整wsrep_slave_threads或者把节点剔除
+---------------------------+----------+
| Variable_name | Value |
+---------------------------+----------+
| wsrep_flow_control_paused | 0.000000 |
+---------------------------+----------+
3、wsrep_cert_deps_distance显示了平行apply的最低和最高排序编号或者sql编号之间的平均距离值。这代表了节点潜在的并行程度，和线程相关
+--------------------------+----------+
| Variable_name | Value |
+--------------------------+----------+
| wsrep_cert_deps_distance | 1.000000 |
+--------------------------+----------+
四、检测网络慢的问题
通过检查发送队列来看传出的连接状况
1、wsrep_local_send_queue_avg显示自上次查询之后的平均发送队列长度。比如网络瓶颈和flow control都可能是原因
+----------------------------+----------+
| Variable_name | Value |
+----------------------------+----------+
| wsrep_local_send_queue_avg | 0.033333 |
+----------------------------+----------+
wsrep_local_send_queue_max 和 wsrep_local_send_queue_min可以看队列设置的最大值和最小值
五、日志监控
在my.cnf中做如下配置
# wsrep Log Options
wsrep_log_conflicts=ON #会将冲突信息写入错误日志中，例如两个节点同时写同一行数据
wsrep_provider_options="cert.log_conflicts=ON" #复制过程中的错误信息写在日志中
wsrep_debug=ON #显示debug 信息在日志中，其中也包括鉴权信息，例如账号密码。因此在生产环境中不开启
六、附加的日志
当某节点在从节点上应用一个事件失败时，数据库服务器会创建一个特殊的binary log文件。文件名默认是GRA_*.log