KingbaseES V8R3集群运维案例之---备库状态‘down’修复

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案例说明：

Kingbase V8R3集群，集群启动正常，备库数据库服务正常，流复制状态正常。但是备库在show pool_nodes下查看是‘down’状态，通过pcp_attach_node重新注册节点后，仍然是‘down’，通过复制（cp）主库data方式重建备库后，仍然没有解决。

此文档，详细介绍了此问题的分析和解决过程。

适用版本：

KingbaseES V8R3

集群节点信息：

一、问题现象

1、节点状态信息

TEST=# show pool_nodes;
 node_id |   hostname    | port  | status | lb_weight |  role   | select_cnt | load_balance_node | replication_delay
---------+---------------+-------+--------+-----------+---------+------------+-------------------+-------------------
 0       | 192.168.1.101 | 54321 | up     | 0.500000  | primary | 0          | true              | 0
 1       | 192.168.1.102 | 54321 | down   | 0.500000  | standby | 0          | false             | 0
(2 rows)

### 如上所示，备库节点状态‘down’。

2、流复制状态信息

TEST=# select * from sys_stat_replication;
  PID  | USESYSID | USENAME | APPLICATION_NAME |  CLIENT_ADDR  | CLIENT_HOSTNAME | CLIENT_PORT |         BACKEND_START         |BACKEND_XMIN |   STATE   | SENT_LOCATION | WRITE_LOCATION | FLUSH_LOCATION | REPLAY_LOCATION | SYNC_PRIORITY | SYNC_STATE
-------+----------+---------+------------------+---------------+-----------------+-------------+-------------------------------+--------------+-----------+---------------+----------------+----------------+-----------------+---------------+------------
 11393 |       10 | SYSTEM  | node102          | 192.168.1.102 |                 |       28251 | 2022-09-21 16:25:46.638372+08 |             | streaming | 2/41237A0     | 2/41237A0      | 2/41237A0      | 2/41237A0       |             2 | sync
(1 row)

二、问题分析和解决

Tips：

一般对于以上问题，可以通过pcp_attach_node方式注册节点，恢复到‘up’状态。

1、注册备库节点

[kingbase@node101 bin]$ ./pcp_attach_node -U kingbase 1
Password:
pcp_attach_node -- Command Successful
[kingbase@node101 bin]$ ./pcp_node_info -U kingbase  1
Password:
192.168.1.102 54321 1 0.500000 waiting
[kingbase@node101 bin]$ ./pcp_node_info -U kingbase  1
Password:
192.168.1.102 54321 2 0.500000 up
[kingbase@node101 bin]$ ./pcp_node_info -U kingbase  1
Password:
192.168.1.102 54321 3 0.500000 down

##如上所示，执行备库节点注册后仍然是‘down’状态。

2、查看备库recovery.log

......
primary node/Im node status is changed, primary ip[192.168.1.101], recovery.conf NEED_CHANGE [0] (0 is need ), I,m status is [1] (1 is down), I will be in recovery.
 node_id |   hostname    | port  | status | lb_weight |  role   | select_cnt | load_balance_node | replication_delay
---------+---------------+-------+--------+-----------+---------+------------+-------------------+-------------------
 0       | 192.168.1.101 | 54321 | up     | 0.500000  | primary | 0          | true              | 0
 1       | 192.168.1.102 | 54321 | down   | 0.500000  | standby | 0          | false             | 0
(2 rows)

if recover node up, let it down , for rewind
waiting for server to shut down.... done
server stopped
2022-09-21 16:18:36 set /home/kingbase/cluster/R3HA/db/data down now... already down , check again
wait kb stop 5 sec .......
2022-09-21 16:18:37 sys_rewind...
sys_rewind  --target-data=/home/kingbase/cluster/R3HA/db/data --source-server="host=192.168.1.101 port=54321 user=SUPERMANAGER_V8ADMIN dbname=TEST"
datadir_source = /home/kingbase/cluster/R3HA/db/data
rewinding from last common checkpoint at 2/125C2A0 on timeline 19
find last common checkpoint start time from 2022-09-21 16:18:37.147787 CST to 2022-09-21 16:18:37.178836 CST, in "0.031049" seconds.
reading source file list
reading target file list
reading WAL in target
Rewind datadir file from source
update the control file: minRecoveryPoint is '2/127FA40', minRecoveryPointTLI is '19', and database state is 'in archive recovery'
rewind start wal location 2/125C268 (file 000000130000000200000001), end wal location 2/127FA40 (file 000000130000000200000001). time from 2022-09-21 16:18:37.147787 CST to 2022-09-21 16:18:38.887227 CST, in "1.739440" seconds.
Done!

server started
ksql "port=54321 user=SUPERMANAGER_V8ADMIN dbname=TEST connect_timeout=10"   -c "select 33333;"
 SYS_CREATE_PHYSICAL_REPLICATION_SLOT
--------------------------------------
 (slot_node101,)
(1 row)

2022-09-21 16:18:43 create the slot [slot_node101] success.
 SYS_CREATE_PHYSICAL_REPLICATION_SLOT
--------------------------------------
 (slot_node102,)
(1 row)

2022-09-21 16:18:43 create the slot [slot_node102] success.
2022-09-21 16:18:43 start up standby successful!
can not get the replication of myself

---日志显示，在执行pcp_attach_node后，执行sys_rewind做节点的recovery，
sys_rewind执行成功，备库仍然为‘down’状态。

3、查看备库recovery配置文件

1）recovery.conf 配置

[kingbase@node102 data]$ cat recovery.conf
standby_mode='on'
primary_conninfo='port=54321 host=192.168.1.101 user=SYSTEM password=MTIzNDU2 application_name=node101
primary_slot_name ='slot_node101'

2）备库etc/recovery.done

[kingbase@node102 data]$ cat etc/recovery.done
standby_mode='on'
primary_conninfo='port=54321 host=192.168.1.101 user=SYSTEM password=MTIzNDU2 application_name=node101
primary_slot_name ='slot_node101'

3）查看主库recovery.done

[kingbase@node101 bin]$ cat ../data/recovery.done
standby_mode='on'
primary_conninfo='port=54321 host=192.168.1.102 user=SYSTEM password=MTIzNDU2 application_name=node101'
recovery_target_timeline='latest'
primary_slot_name ='slot_node101'

4、查看备库复制槽信息

TEST=# select * from sys_replication_slots;
  SLOT_NAME   | PLUGIN | SLOT_TYPE | DATOID | DATABASE | ACTIVE | ACTIVE_PID |  XMIN  | CATALOG_XMIN | RESTART_LSN | CONFIRMED_FL
USH_LSN
--------------+--------+-----------+--------+----------+--------+------------+--------+--------------+-------------+-------------
--------
 slot_node101 |        | physical  |        |          | t      |       6937 | 114712 |              | 2/12A1468   |
 slot_node102 |        | physical  |        |          | f      |            | 113518 |              | 1/FD000878  |
(2 rows)

###由于备库recovery.conf配置问题，导致流复制备库应用了错误的复制槽。

四、问题解决

1、修改备库recovery.conf

[kingbase@node102 data]$ cat recovery.conf
standby_mode='on'
primary_conninfo='port=54321 host=192.168.1.101 user=SYSTEM password=MTIzNDU2 application_name=node102
primary_slot_name ='slot_node102'

2、 备库etc/recovery.done

[kingbase@node102 data]$ cat etc/recovery.done
standby_mode='on'
primary_conninfo='port=54321 host=192.168.1.101 user=SYSTEM password=MTIzNDU2 application_name=node102
primary_slot_name ='slot_node102'

3、关闭备库数据库服务

[kingbase@node102 bin]$ ./sys_ctl stop -D ../data
waiting for server to shut down.... done
server stopped

4、删除复制槽

TEST=# select sys_drop_replication_slot('slot_node101');
 SYS_DROP_REPLICATION_SLOT
---------------------------

(1 row)

5、重启集群

[kingbase@node101 bin]$ ./kingbase_monitor.sh restart

6、查看节点状态

TEST=# show pool_nodes;
 node_id |   hostname    | port  | status | lb_weight |  role   | select_cnt | load_balance_node | replication_delay
---------+---------------+-------+--------+-----------+---------+------------+-------------------+-------------------
 0       | 192.168.1.101 | 54321 | up     | 0.500000  | primary | 0          | true              | 0
 1       | 192.168.1.102 | 54321 | up     | 0.500000  | standby | 0          | false             | 0
(2 rows)

[kingbase@node101 bin]$ ./pcp_node_info -U kingbase 1
Password:
192.168.1.102 54321 2 0.500000 up
[kingbase@node101 bin]$ ./pcp_node_info -U kingbase 0
Password:
192.168.1.101 54321 2 0.500000 up

###如上所示，备库节点已经正常。

7、查看备库recovery.log

.......
2022-09-21 16:37:02 check if the network is ok
ping trust ip 192.168.1.1 success ping times :[3], success times:[2]
determine if i am master or standby
 node_id |   hostname    | port  | status | lb_weight |  role   | select_cnt | load_balance_node | replication_delay
---------+---------------+-------+--------+-----------+---------+------------+-------------------+-------------------
 0       | 192.168.1.101 | 54321 | up     | 0.500000  | primary | 0          | false             | 0
 1       | 192.168.1.102 | 54321 | up     | 0.500000  | standby | 0          | true              | 0
(2 rows)

i am standby in cluster,determine if recovery is needed
2022-09-21 16:37:04 now will del vip [192.168.1.200/24]
but no 192.168.1.200/24 on my DEV, nothing to do with del
cluster is sync cluster.
now,there is a synchronous standby.
2022-09-21 16:37:07 ALL NODES ARE UP STATUS!
2022-09-21 16:37:07 ALL NODES ARE UP STATUS!

###如上所示，recovery.log中备库状态信息已经正常。

五、总结

1、 对于集群出现的问题，要从多个方面进行分析、判断，找到问题发生的根本原因。

2、对于备库的clone，尽量不要使用静态copy方式，此种方式备库需修改的文件较多，难免有遗漏，出现集群故障问题。

3、建议使用sys_basebackup执行备库clone，clone后注意检查备库集群配置文件。