test-rs0:PRIMARY> db.getSiblingDB("local").system.replset.findOne()
{
	"_id" : "test-rs0",
	"version" : 1,
	"members" : [
		{
			"_id" : 0,
			"host" : "Jonathans-MacBook-Pro.local:31100"
		},
		{
			"_id" : 1,
			"host" : "Jonathans-MacBook-Pro.local:31101"
		},
		{
			"_id" : 2,
			"host" : "Jonathans-MacBook-Pro.local:31102"
		}
	]
}
test-rs0:PRIMARY> db.orphan.find({orphan:true}).count();
99
test-rs0:PRIMARY> cd
{
	"cleanupOrphaned" : "test.orphan",
	"startingAtKey" : {
		"shardKey" : 0
	},
	"secondaryThrottle" : true,
	"writeConcern" : {
		"w" : "nodc"
	}
}
test-rs0:PRIMARY> db.adminCommand(cd);
{
	"ok" : 0,
	"errmsg" : "Error encountered while deleting range: nstest.orphan from { shardKey: MinKey } -> { shardKey: 500.0 }, cause by: :: caused by :: 79 No write concern mode named \"nodc found in replica set configuration"
}
test-rs0:PRIMARY> db.orphan.find({orphan:true}).count();
98

test-rs0:PRIMARY> conf=db.getSiblingDB("local").system.replset.findOne()
{
	"_id" : "test-rs0",
	"version" : 2,
	"members" : [
		{
			"_id" : 0,
			"host" : "Jonathans-MacBook-Pro.local:31100",
			"priority" : 100,
			"tags" : {
				"main" : "NY"
			}
		},
		{
			"_id" : 1,
			"host" : "Jonathans-MacBook-Pro.local:31101",
			"priority" : 2,
			"tags" : {
				"backup" : "SF"
			}
		},
		{
			"_id" : 2,
			"host" : "Jonathans-MacBook-Pro.local:31102",
			"priority" : 2,
			"tags" : {
				"main" : "NY"
			}
		}
	],
	"settings" : {
		"getLastErrorModes" : {
			"alldc" : {
				"main" : 1,
				"backup" : 1
			},
			"maindc" : {
				"main" : 1
			}
		}
	}
}
test-rs0:PRIMARY> cd={cleanupOrphaned: "test.orphan", startingAtKey:{shardKey:0},     secondaryThrottle:true, writeConcern: {w: "maindc"}}
test-rs0:PRIMARY> db.adminCommand(cd);
{ "stoppedAtKey" : { "shardKey" : 500 }, "ok" : 1 }
test-rs0:PRIMARY> db.orphan.find({orphan:true}).count();
0
test-rs0:PRIMARY> for (i=0;i<100;i++) {     db.orphan.insert({shardKey:i, orphan: true}) }

WriteResult({ "nInserted" : 1 })
test-rs0:PRIMARY> db.orphan.find({orphan:true}).count();
100
test-rs0:PRIMARY> cd={cleanupOrphaned: "test.orphan", startingAtKey:{shardKey:0},     secondaryThrottle:true, writeConcern: {w: "main"}}
test-rs0:PRIMARY> db.adminCommand(cd);
{
	"ok" : 0,
	"errmsg" : "Error encountered while deleting range: nstest.orphan from { shardKey: MinKey } -> { shardKey: 500.0 }, cause by: :: caused by :: 79 No write concern mode named \"main found in replica set configuration"
}
test-rs0:PRIMARY> db.orphan.find({orphan:true}).count();
99

test-rs0:PRIMARY> db.orphan.insert({shardKey:200,orphan:true},{w: "nodc"})
WriteResult({ "nInserted" : 1 })