Hi,

I have found in MongoDB documentation that "An ISODate formatted date string that reflects the last entry from the oplog that this member applied. If this differs significantly from lastHeartbeat this member is either experiencing “replication lag” or there have not been any new operations since the last update"

My question is,Is there any particular calculation or some thing else through which I can measure replication lag.

Below is the statics on basis of that I want to check any Replication Lag.

"members" : [
{

"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 1137376,
"optime" :

{ "t" : 1369035838, "i" : 2 }

,
"optimeDate" : ISODate("2013-05-20T07:43:58Z"),
"lastHeartbeat" : ISODate("2013-05-20T11:41:24Z"),
"lastHeartbeatRecv" : ISODate("2013-05-20T11:41:25Z"),
"pingMs" : 0,

},
{
"_id" : 1,
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 1139161,
"optime" :

{ "t" : 1369035838, "i" : 2 }

,
"optimeDate" : ISODate("2013-05-20T07:43:58Z"),
"self" : true
},
{
"_id" : 2,
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 1137376,
"optime" :

{ "t" : 1369035838, "i" : 2 }

,
"optimeDate" : ISODate("2013-05-20T07:43:58Z"),
"lastHeartbeat" : ISODate("2013-05-20T11:41:24Z"),
"lastHeartbeatRecv" : ISODate("1970-01-01T00:00:00Z"),
"pingMs" : 0,

}
],

Thanks
MANISH