mongodb 集群重構和釋放磁盤空間實例詳解

2020-03-14 13:04:41

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MongoDB集群重構，釋放磁盤空間

由于mongodb刪除了一部分數據后，不會回收相應的磁盤空間，所以這里通過重建數據目錄的方式釋放磁盤空間。

一實驗環境

配置了一個副本集，該副本集由以下三個節點組成：

10.192.203.201:27017 PRIMARY

10.192.203.202:27017 SECONDARY

10.192.203.202:10001 ARBITER

二實驗步驟

2.1 模擬環境

use dba; for(var i=0;i<1000000;i++)db.c.insert({uid:i,uname:'osqlfan'+i}); db.c.find().count();#1000000  db.stats(); {   "db" : "dba",   "collections" : 5,   "objects" : 1000111,   "avgObjSize" : 111.9994880568257,   "dataSize" : 112011920,   "storageSize" : 174796800,   "numExtents" : 17,   "indexes" : 3,   "indexSize" : 32475072,   "fileSize" : 469762048,   "nsSizeMB" : 16,   "extentFreeList" : {     "num" : 0,     "totalSize" : 0   },   "dataFileVersion" : {     "major" : 4,     "minor" : 22   },   "ok" : 1 }

磁盤空間增加了400M數據：

-rw-------. 1 root root 134217728 Nov 7 13:38 dba.1

-rw-------. 1 root root 268435456 Nov 7 13:38 dba.2

[root@slave2 ~]# du -sh /data/mongo/data

4.7G /data/mongo/data

#刪除dba.c表數據: MyReplset:PRIMARY> db.c.drop(); true MyReplset:PRIMARY> db.c.find().count(); 0 MyReplset:PRIMARY> db.stats(); { "db" : "dba", "collections" : 4, "objects" : 108, "avgObjSize" : 108.44444444444444, "dataSize" : 11712, "storageSize" : 61440, "numExtents" : 5, "indexes" : 2, "indexSize" : 16352, "fileSize" : 469762048, "nsSizeMB" : 16, "extentFreeList" : { "num" : 18, "totalSize" : 212492288 }, "dataFileVersion" : { "major" : 4, "minor" : 22 }, "ok" : 1 }

看到dataSize，indexSize，storageSize都變小了，但是fileSize沒有變化，而且mongo data目錄仍然占用4.7G。

2.2 確保先在從庫10.192.203.202:27017上進行重構

#查看主從關系

MyReplset:PRIMARY>rs.status(); { "set" : "MyReplset", "date" :ISODate("2016-11-07T07:10:50.717Z"), "myState" : 1, "members" : [       {           "_id" : 0,           "name" :"10.192.203.201:27017",           "health" : 1,           "state" : 1,           "stateStr" :"PRIMARY",           "uptime" : 964,           "optime" :Timestamp(1478239977, 594),           "optimeDate" :ISODate("2016-11-04T06:12:57Z"),           "electionTime" :Timestamp(1478502021, 1),           "electionDate" :ISODate("2016-11-07T07:00:21Z"),           "configVersion" :2,           "self" : true       },       {           "_id" : 1,           "name" :"10.192.203.202:27017",           "health" : 1,           "state" : 2,           "stateStr" :"SECONDARY",           "uptime" : 628,           "optime" :Timestamp(1478239977, 594),           "optimeDate" :ISODate("2016-11-04T06:12:57Z"),           "lastHeartbeat" :ISODate("2016-11-07T07:10:49.257Z"),           "lastHeartbeatRecv": ISODate("2016-11-07T07:10:50.143Z"),           "pingMs" : 2,           "configVersion" :2       },       {           "_id" : 2,           "name" :"10.192.203.202:10001",           "health" : 1,           "state": 7,           "stateStr" :"ARBITER",           "uptime" : 618,           "lastHeartbeat" :ISODate("2016-11-07T07:10:49.416Z"),           "lastHeartbeatRecv": ISODate("2016-11-07T07:10:49.847Z"),           "pingMs" : 2,           "configVersion" :2       } ], "ok" : 1 }

2.2.1 關閉數據庫

MyReplset:SECONDARY> use admin; switched to db admin MyReplset:SECONDARY> db.shutdownServer(); 2016-11-07T15:14:42.548+0800 I NETWORK DBClientCursor::init call() failed server should be down... 2016-11-07T15:14:42.571+0800 I NETWORK trying reconnect to 127.0.0.1:27017(127.0.0.1) failed 2016-11-07T15:14:42.575+0800 W NETWORK Failed to connect to 127.0.0.1:27017, reason:errno:111 Connection refused 2016-11-07T15:14:42.575+0800 I NETWORK reconnect 127.0.0.1:27017 (127.0.0.1) failedfailed couldn't connect to server 127.0.0.1:27017 (127.0.0.1), connectionattempt failed 2016-11-07T15:14:42.634+0800 I NETWORK trying reconnect to 127.0.0.1:27017(127.0.0.1) failed 2016-11-07T15:14:42.637+0800 W NETWORK Failed to connect to 127.0.0.1:27017, reason:errno:111 Connection refused 2016-11-07T15:14:42.638+0800I NETWORK reconnect 127.0.0.1:27017(127.0.0.1) failed failed couldn't connect to server 127.0.0.1:27017(127.0.0.1), connection attempt failed

2.2.2 備份，刪除，重建數據目錄

備份10.192.203.202:27017的數據目錄，這里省略

備份完成后，刪除，重建該目錄。

rm-rf /data/mongo/data

mkdir/data/mongo/data

2.2.3 啟動數據庫

啟動10.192.203.202:27017進程:

/usr/local/mongodb/bin/mongod--config /usr/local/mongodb/mongod.cnf --replSet MyReplset -rest

2.2.4 檢查

檢查數據庫是否正常，之前的數據庫是否都存在。

檢查下磁盤空間是否縮小。

經檢查，空間縮小為4.3G，收縮了400MB。