MongoDB主备仲裁节点关闭顺序
MongoDB分为三个角色节点：Primary（P）、Secondary（S）、Arbiter（A），但是关闭顺序不正确，关闭时就会有问题，有些时候，关闭后启动也会有问题。
因此需要有一个正确的顺序来关闭MongoDB集群。下方为实验顺序：
1：关闭顺序PSA ：会报错
2：关闭顺序PAS ：可以
3：关闭顺序SAP ：主节点会变为从节点
4：关闭顺序SPA ：会报错
5：关闭顺序APS
6：关闭顺序ASP ：主节点会变为从节点服务查看：
gechongrepl:PRIMARY> rs.isMaster()
{
"setName" : "gechongrepl",
"setVersion" : 13,
"ismaster" : true,
"secondary" : false,
"hosts" : [
"192.168.91.133:27017",
"192.168.91.132:27017",
"192.168.91.132:27018"
],
"arbiters" : [
"192.168.91.135:27017"
],
"primary" : "192.168.91.133:27017",
"me" : "192.168.91.133:27017",
"electionId" : ObjectId("5568098a6de3d53a2ea91c64"),
"maxBsonObjectSize" : 16777216,
"maxMessageSizeBytes" : 48000000,
"maxWriteBatchSize" : 1000,
"localTime" : ISODate("2015-05-29T06:39:36.548Z"),
"maxWireVersion" : 3,
"minWireVersion" : 0,
"ok" : 1
}1：关闭顺序PSA
P：
gechongrepl:PRIMARY> use admin
switched to db admin
gechongrepl:PRIMARY> db.shutdownServer()S：
从变为了：gechongrepl:PRIMARY>
<br><br>gechongrepl:PRIMARY> use admin
switched to db admin
gechongrepl:PRIMARY> db.shutdownServer()
assert failed : unexpected error: Error: shutdownServer failed: No electable secondaries caught up as of 2015-05-28T23:48:06.022-0700
Error: assert failed : unexpected error: Error: shutdownServer failed: No electable secondaries caught up as of 2015-05-28T23:48:06.022-0700
at Error (<anonymous>)
at doassert (src/mongo/shell/assert.js:11:14)
at assert (src/mongo/shell/assert.js:20:5)
at DB.shutdownServer (src/mongo/shell/db.js:212:9)
at (shell):1:4
2015-05-28T23:48:06.023-0700 E QUERY Error: assert failed : unexpected error: Error: shutdownServer failed: No electable secondaries caught up as of 2015-05-28T23:48:06.022-0700
at Error (<anonymous>)
at doassert (src/mongo/shell/assert.js:11:14)
at assert (src/mongo/shell/assert.js:20:5)
at DB.shutdownServer (src/mongo/shell/db.js:212:9)
at (shell):1:4 at src/mongo/shell/assert.js:13A：
gechongrepl:ARBITER> use admin
switched to db admin
gechongrepl:ARBITER> db.shutdownServer()再关闭S：
S变为了：ggechongrepl:SECONDARY>
gechongrepl:SECONDARY> use admin
switched to db admin
gechongrepl:SECONDARY> db.shutdownServer()2：关闭顺序PAS : 已经验证，不报错。
3：关闭顺序SAP
S：
gechongrepl:SECONDARY> use admin
switched to db admin
gechongrepl:SECONDARY> db.shutdownServer()A：
gechongrepl:ARBITER> use admin
switched to db admin
gechongrepl:ARBITER> db.shutdownServer()P：
主变为了：gechongrepl:SECONDARY>
gechongrepl:SECONDARY> use admin
switched to db admin
gechongrepl:SECONDARY> db.shutdownServer()4：关闭顺序SPA
S：
gechongrepl:SECONDARY> use admin
switched to db admin
gechongrepl:SECONDARY> db.shutdownServer()P：
gechongrepl:PRIMARY> use admin
switched to db admin
gechongrepl:PRIMARY> db.shutdownServer()
assert failed : unexpected error: Error: shutdownServer failed: No electable secondaries caught up as of 2015-05-28T23:59:19.685-0700
Error: assert failed : unexpected error: Error: shutdownServer failed: No electable secondaries caught up as of 2015-05-28T23:59:19.685-0700
at Error (<anonymous>)
at doassert (src/mongo/shell/assert.js:11:14)
at assert (src/mongo/shell/assert.js:20:5)
at DB.shutdownServer (src/mongo/shell/db.js:212:9)
at (shell):1:4
2015-05-28T23:59:19.702-0700 E QUERY Error: assert failed : unexpected error: Error: shutdownServer failed: No electable secondaries caught up as of 2015-05-28T23:59:19.685-0700
at Error (<anonymous>)
at doassert (src/mongo/shell/assert.js:11:14)
at assert (src/mongo/shell/assert.js:20:5)
at DB.shutdownServer (src/mongo/shell/db.js:212:9)
at (shell):1:4 at src/mongo/shell/assert.js:13A：
gechongrepl:ARBITER> use admin
switched to db admin
gechongrepl:ARBITER> db.shutdownServer()再次关闭P：
gechongrepl:PRIMARY> use admin
switched to db admin
2015-05-29T00:00:44.938-0700 I NETWORK DBClientCursor::init call() failed
2015-05-29T00:00:44.940-0700 I NETWORK trying reconnect to 127.0.0.1:27017 (127.0.0.1) failed
2015-05-29T00:00:44.941-0700 I NETWORK reconnect 127.0.0.1:27017 (127.0.0.1) ok
gechongrepl:SECONDARY> db.shutdownServer()5：关闭顺序APS
A：
gechongrepl:ARBITER> use admin
switched to db admin
gechongrepl:ARBITER> db.shutdownServer()P：
gechongrepl:PRIMARY> use admin
switched to db admin
gechongrepl:PRIMARY> db.shutdownServer()S：因为仲裁节点关闭了。所以Primary节点不会再自动切换
gechongrepl:SECONDARY> use admin
switched to db admin
gechongrepl:SECONDARY> db.shutdownServer()6：关闭顺序ASP
A：
gechongrepl:ARBITER> use admin
switched to db admin
gechongrepl:ARBITER> db.shutdownServer()S：
gechongrepl:SECONDARY> use admin
switched to db admin
gechongrepl:SECONDARY> db.shutdownServer()P：
gechongrepl:PRIMARY>
2015-05-29T00:12:23.962-0700 I NETWORK DBClientCursor::init call() failed
2015-05-29T00:12:23.965-0700 I NETWORK trying reconnect to 127.0.0.1:27017 (127.0.0.1) failed
2015-05-29T00:12:23.966-0700 I NETWORK reconnect 127.0.0.1:27017 (127.0.0.1) ok
Primary变为Secondary：
gechongrepl:SECONDARY>
gechongrepl:SECONDARY> use admin
switched to db admin
gechongrepl:SECONDARY> db.shutdownServer()总结：
1：先关闭从节点、仲裁节点。或者先关闭仲裁节点，最后关闭从节点。则：主节点自动变为从节点
2：先关闭主节点，则从节点自动变为主节点，在仲裁节点关闭之前，新主节点不能关闭
初始化的时候主从节点受priority的影响
priority: 是优先级，默认为1，优先级0为被动节点，不能成为活跃节点。优先级不位0则按照有大到小选出活跃节点。
come from:https://www.wencst.com/archives/1809?utm_source=tuicool&utm_medium=referral
