title: MongoDB sharding problems
body: <p>Our mongodb server deployed with 2 shards, each has 1 master server and 2 slave servers. 
  The four slave servers run mongo config as proxy, and two of the slave servers run arbiters.
  But the mongodb coundn't be used now.</p>
  
  <p>I can connect to 192.168.0.1:8000(mongos) and exec queries like 'use database' or 'show dbs', but i cann't exec queries in a choosed database such as 'db.foo.count()', 'db.foo.findOne()'</p>
  
  <p>Here is the error log:</p>
  
  <pre><code>mongos&gt; db.dev.count()
  Fri Aug 16 12:55:36 uncaught exception: count failed: {
      "assertion" : "DBClientBase::findN: transport error: 10.81.4.72:7100 query: { setShardVersion: \"\", init: true, configdb: \"10.81.4.72:7300,10.42.50.26:7300,10.81.51.235:7300\", serverID: ObjectId('520db0a51fa00999772612b9'), authoritative: true }",
      "assertionCode" : 10276,
      "errmsg" : "db assertion failure",
      "ok" : 0
  }
  
  
  
  
  Fri Aug 16 11:23:29 [conn8431] DBClientCursor::init call() failed
  Fri Aug 16 11:23:29 [conn8430] Socket recv() errno:104 Connection reset by peer 10.81.4.72:7100
  Fri Aug 16 11:23:29 [conn8430] SocketException: remote: 10.81.4.72:7100 error: 9001 socket exception [1] server [10.81.4.72:7100] 
  Fri Aug 16 11:23:29 [conn8430] DBClientCursor::init call() failed
  Fri Aug 16 11:23:29 [conn8430] DBException in process: could not initialize cursor across all shards because : DBClientBase::findN: transport error: 10.81.4.72:7100 query: { setShardVersion: "", init: true, configdb: "10.81.4.72:7300,10.42.50.26:7300,10.81.51.235:7300", serverID: ObjectId('520d99c972581e6a124d0561'), authoritative: true } @ s01/10.36.31.36:7100,10.42.50.24:7100,10.81.4.72:7100
  </code></pre>
  
  <p>i can only start on mongos, queries wouldn't be exec if more than 1 mongos run at the same time, error log: </p>
  
  <pre><code>mongos&gt; db.dev.count() Fri Aug 16 15:12:29 uncaught exception: count failed: { "assertion" : "DBClientBase::findN: transport error: 10.81.4.72:7100 query: { setShardVersion: \"\", init: true, configdb: \"10.81.4.72:7300,10.42.50.26:7300,10.81.51.235:7300\", serverID: ObjectId('520dd04967557902f73a9fba'), authoritative: true }", "assertionCode" : 10276, "errmsg" : "db assertion failure", "ok" : 0 }
  </code></pre>