At bash prompt: mlaunch init --sharded 3 --replicaset mongo Note: I'm using mlaunch version 1.1.6 At the mongo shell: for (i=1; i<=1000; i++ ) {x = []; for (j=1; j<=1000; j++) {x.push( { a : i, b : j, c : 1000 * i + j, _id : 1000 * i + j } )}; db.foo.insert(x) } db.foo.ensureIndex( { a : 1, b : 1 }, { name : "first" } ) db.foo.ensureIndex( { b : 1 }, { name : "second" } ) sh.enableSharding( "test" ) sh.shardCollection( "test.foo" , { b : 1 } ) Run sh.status() repeatedly until you catch it with the balancer on. Expected result: All fields in sh.status() get populated. Actual result: Take a look at the line that says "Balancer lock taken at undefined by undefined". mongos> sh.status() --- Sharding Status --- sharding version: { "_id" : 1, "minCompatibleVersion" : 5, "currentVersion" : 6, "clusterId" : ObjectId( "5492159f53be077898567039" ) } shards: { "_id" : "shard01" , "host" : "shard01/cross-mb-air.local:27018,cross-mb-air.local:27019,cross-mb-air.local:27020" } { "_id" : "shard02" , "host" : "shard02/cross-mb-air.local:27021,cross-mb-air.local:27022,cross-mb-air.local:27023" } { "_id" : "shard03" , "host" : "shard03/cross-mb-air.local:27024,cross-mb-air.local:27025,cross-mb-air.local:27026" } balancer: Currently enabled: yes Currently running: yes Balancer lock taken at undefined by undefined Collections with active migrations: test.foo started at Wed Dec 17 2014 19:05:28 GMT-0500 (EST) Failed balancer rounds in last 5 attempts: 0 Migration Results for the last 24 hours: 3 : Success 2 : Failed with error 'chunk too big to move' , from shard01 to shard03 1 : Failed with error 'chunk too big to move' , from shard01 to shard02 databases: { "_id" : "admin" , "partitioned" : false , "primary" : "config" } { "_id" : "test" , "partitioned" : true , "primary" : "shard01" } test.foo shard key: { "b" : 1 } chunks: shard01 4 shard02 2 shard03 1 { "b" : { "$minKey" : 1 } } -->> { "b" : 1 } on : shard02 Timestamp(2, 0) { "b" : 1 } -->> { "b" : 150 } on : shard03 Timestamp(3, 0) { "b" : 150 } -->> { "b" : 300 } on : shard02 Timestamp(4, 0) { "b" : 300 } -->> { "b" : 450 } on : shard01 Timestamp(4, 2) { "b" : 450 } -->> { "b" : 600 } on : shard01 Timestamp(4, 3) { "b" : 600 } -->> { "b" : 899 } on : shard01 Timestamp(1, 2) { "b" : 899 } -->> { "b" : { "$maxKey" : 1 } } on : shard01 Timestamp(1, 3) mongos>