error: { "$err" : "not master and slaveOk=false", "code" : 13435 }

rsguo:SECONDARY> db.users.find();
error: { "$err" : "not master and slaveOk=false", "code" : 13435 }

错误原因：

这是正常的，因为SECONDARY是不允许读写的，如果非要解决，方法如下：

rsguo:SECONDARY> rs.slaveOk();

再次查询，即可正常：
rsguo:SECONDARY> db.users.find();
{ "_id" : ObjectId("5a1529667fd02f4b95ceba88"), "name" : "liang", "age" : 28 }
{ "_id" : ObjectId("5a15298d7fd02f4b95ceba89"), "name" : "guo", "age" : 27 }
{ "_id" : ObjectId("5a15298d7fd02f4b95ceba8a"), "name" : "jun", "age" : 26 }
{ "_id" : ObjectId("5a15298d7fd02f4b95ceba8b"), "name" : "guang", "age" : 25 }
{ "_id" : ObjectId("5a15298e7fd02f4b95ceba8c"), "name" : "xi", "age" : 24 }