如某个节点出现永久性故障，不可修复，且剩余节点也足以支撑现有业务，GBase 8a 可以通过缩容，重建集群主备关系，来剔除故障节点。本文通过一个实际例子介绍操作过程。
本文故障节点，指数据计算节点。 强烈建议管理，调度和计算节点分别部署，避免混用，除非节点少，成本优先。
环境
3节点集群，其中115节点故障。本此操作，不仅将故障的115缩容，顺便将102节点也缩容。
数据库为9.5.2
[gbase@gbase_rh7_001 ~]$ gcadmin
CLUSTER STATE: ACTIVE
VIRTUAL CLUSTER MODE: NORMAL
=============================================================
| GBASE COORDINATOR CLUSTER INFORMATION |
=============================================================
| NodeName | IpAddress | gcware | gcluster | DataState |
-------------------------------------------------------------
| coordinator1 | 10.0.2.101 | OPEN | OPEN | 0 |
-------------------------------------------------------------
=========================================================================================================
| GBASE DATA CLUSTER INFORMATION |
=========================================================================================================
| NodeName | IpAddress | DistributionId | gnode | syncserver | DataState |
---------------------------------------------------------------------------------------------------------
| node1 | 10.0.2.101 | 7 | OPEN | OPEN | 0 |
---------------------------------------------------------------------------------------------------------
| node2 | 10.0.2.102 | 7 | OPEN | OPEN | 0 |
---------------------------------------------------------------------------------------------------------
| node3 | 10.0.2.115 | 7 | CLOSE | CLOSE | 0 |
---------------------------------------------------------------------------------------------------------缩容操作
与普通缩容过程完全一样，主要为了证明在节点故障时，也是可以缩容的。
创建不包含故障节点，以及计划缩容节点的分布策略
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ cat gcChangeInfo_one.xml
<?xml version="1.0" encoding="utf-8"?>
<servers>
<rack>
<node ip="10.0.2.101"/>
</rack>
</servers>创建新的策略
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ gcadmin distribution gcChangeInfo_one.xml p 1 d 0
gcadmin generate distribution ...
[warning]: parameter [d num] is 0, the new distribution will has no segment backup
please ensure this is ok, input [Y,y] or [N,n]: y
gcadmin generate distribution successful
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ 初始化和重分布
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ gccli
GBase client 9.5.2.44.1045e3118. Copyright (c) 2004-2022, GBase. All Rights Reserved.
gbase> initnodedatamap;
Query OK, 0 rows affected, 3 warnings (Elapsed: 00:00:00.53)
gbase> rebalance instance;
Query OK, 11 rows affected (Elapsed: 00:00:00.74)等待重分布结束
清理环境
删除nodedatamap
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ gccli
GBase client 9.5.2.44.1045e3118. Copyright (c) 2004-2022, GBase. All Rights Reserved.
gbase> refreshnodedatamap drop 7;
Query OK, 0 rows affected, 3 warnings (Elapsed: 00:00:00.62)
gbase> ^CAborted
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$清理event，因为重分布时，会导致故障节点出现ddl/dml的event.
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ gcadmin rmdmlevent 2 10.0.2.115
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ gcadmin rmddlevent 2 10.0.2.115删除分布策略
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ gcadmin rmdistribution 7
cluster distribution ID [7]
it will be removed now
please ensure this is ok, input [Y,y] or [N,n]: y
gcadmin remove distribution [7] success
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ gcadmin
CLUSTER STATE: ACTIVE
VIRTUAL CLUSTER MODE: NORMAL
=============================================================
| GBASE COORDINATOR CLUSTER INFORMATION |
=============================================================
| NodeName | IpAddress | gcware | gcluster | DataState |
-------------------------------------------------------------
| coordinator1 | 10.0.2.101 | OPEN | OPEN | 0 |
-------------------------------------------------------------
=========================================================================================================
| GBASE DATA CLUSTER INFORMATION |
=========================================================================================================
| NodeName | IpAddress | DistributionId | gnode | syncserver | DataState |
---------------------------------------------------------------------------------------------------------
| node1 | 10.0.2.101 | 8 | OPEN | OPEN | 0 |
---------------------------------------------------------------------------------------------------------
| node2 | 10.0.2.102 | | OPEN | OPEN | 0 |
---------------------------------------------------------------------------------------------------------
| node3 | 10.0.2.115 | | CLOSE | CLOSE | 0 |
---------------------------------------------------------------------------------------------------------
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$移除缩容的节点
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ cat rmnodes.xml
<?xml version="1.0" encoding="utf-8"?>
<servers>
<rack>
<node ip="10.0.2.102"/>
<node ip="10.0.2.115"/>
</rack>
</servers>
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ gcadmin rmnodes rmnodes.xml
gcadmin remove nodes ...
gcadmin rmnodes from cluster success
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$ gcadmin
CLUSTER STATE: ACTIVE
VIRTUAL CLUSTER MODE: NORMAL
=============================================================
| GBASE COORDINATOR CLUSTER INFORMATION |
=============================================================
| NodeName | IpAddress | gcware | gcluster | DataState |
-------------------------------------------------------------
| coordinator1 | 10.0.2.101 | OPEN | OPEN | 0 |
-------------------------------------------------------------
=========================================================================================================
| GBASE DATA CLUSTER INFORMATION |
=========================================================================================================
| NodeName | IpAddress | DistributionId | gnode | syncserver | DataState |
---------------------------------------------------------------------------------------------------------
| node1 | 10.0.2.101 | 8 | OPEN | OPEN | 0 |
---------------------------------------------------------------------------------------------------------
[gbase@gbase_rh7_001 gcinstall_9.5.2.44.10]$删除缩容节点的数据库文件
rm -fr /opt/gbase/gcluster
rm -fr /opt/gbase/gnode
rm -fr /opt/gbase/gcware总结
当节点彻底不可用时，GBase 8a集群是支持将该节点强制缩容剔除出集群的。与正常缩容的区别，就是缩容重分布过程会在故障节点产生event,再删除分布策略时要先清理掉。
