查看MongoDB中Replica Set的狀態

查看Replica Set的狀態，執行rs.status()即可

rs.status()
{
        "set" : "set1",
        "date" : "Thu Oct 28 2010 10:09:28 GMT+0800 (CST)",
        "myState" : 2,
        "members" : [
                {
                        "_id" : 0,
                        "name" : "192.168.95.216:10000",
                        "health" : 1,
                        "state" : 1,
                        "uptime" : 2486042,
                        "lastHeartbeat" : "Thu Oct 28 2010 10:09:26 GMT+0800 (CST)"
                },
                {
                        "_id" : 1,
                        "name" : "zjm-Hadoop-slave217:10000",
                        "health" : 1,
                        "state" : 2,
                        "self" : true
                },
                {
                        "_id" : 2,
                        "name" : "192.168.95.218:10001",
                        "health" : 1,
                        "state" : 7,
                        "uptime" : 2486042,
                        "lastHeartbeat" : "Thu Oct 28 2010 10:09:27 GMT+0800 (CST)"
                }
        ],
        "ok" : 1
}

其中，health為1表明伺服器正常，0表明伺服器down了

state為1表明是Primary，2表明是Secondary，3是Recovering，7是Arbiter，8是Down

如果想在Secondary上find資料，需要先執行以下命令：

db.getMongo().setSlaveOk();
db.suv.find().count()

要查看某個Collection的資訊，可以用db.suv.stats()

{
        "ns" : "suv.suv",
        "count" : 9519581,
        "size" : 573341552,
        "avgObjSize" : 60.2276037149114,
        "storageSize" : 736285696,
        "numExtents" : 21,
        "nindexes" : 3,
        "lastExtentSize" : 129238272,
        "paddingFactor" : 1,
        "flags" : 1,
        "totalIndexSize" : 1612344128,
        "indexSizes" : {
                "_id_" : 462365632,
                "Lt_1" : 790758336,
                "Cl.Cid_1" : 359220160
        },
        "ok" : 1
}

其中：

1. size即為DataSize，是資料所佔的空間大小
2. storageSize為includes free space allocated to this collection，就是說包括已經分配但還閒置空間
3. totalIndexSize為所有索引所佔的空間
4. totalSize為該Collection所佔的總空間，它等於storageSize+totalIndexSize

以上幾個資訊，也可以通過下面命令來查詢：

db.suv.dataSize()
db.suv.storageSize()
db.suv.totalIndexSize()
db.suv.totalSize()