<span style="font-size:18px;">mongos> use dmp
switched to db dmp
mongos> show tables;
2016-08-14T10:02:20.386+0800 E QUERY    [thread1] Error: listCollections failed: {"code" : 133,"ok" : 0,"errmsg" : "could not find host matching read preference { mode: \"primary\", tags: [ {} ] } for set shard3"
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
DB.prototype._getCollectionInfosCommand@src/mongo/shell/db.js:773:1
DB.prototype.getCollectionInfos@src/mongo/shell/db.js:785:19
DB.prototype.getCollectionNames@src/mongo/shell/db.js:796:16
shellHelper.show@src/mongo/shell/utils.js:754:9
shellHelper@src/mongo/shell/utils.js:651:15
@(shellhelp2):1:1mongos> exit</span>

问题3：

</pre><blockquote><blockquote><pre name="code" class="javascript"><span style="font-size:18px;">[mongo@mds4 bin]$ ./mongo --port 28011
MongoDB shell version: 3.2.8
connecting to: 127.0.0.1:28011/test
Server has startup warnings:
2016-08-13T06:33:25.817+0800 I CONTROL  [initandlisten]
2016-08-13T06:33:25.817+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2016-08-13T06:33:25.817+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2016-08-13T06:33:25.817+0800 I CONTROL  [initandlisten]
2016-08-13T06:33:25.817+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2016-08-13T06:33:25.817+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'</span>

处理方法

 <span style="font-size:18px;">   [root@md5 ~]# cat /sys/kernel/mm/transparent_hugepage/defrag[always] madvise never[root@md5 ~]# echo never > /sys/kernel/mm/transparent_hugepage/enabled[root@md5 ~]#  echo never > /sys/kernel/mm/transparent_hugepage/defrag[root@md5 ~]# cat /sys/kernel/mm/transparent_hugepage/defragalways madvise [never][root@md5 ~]# cat /sys/kernel/mm/transparent_hugepage/enabledalways madvise [never][root@md5 ~]# </span>

问题4：

开始设置了oplogszie 为5G,同步完成后，例如出现如下错误：

2016-08-13T06:57:37.810+0800 I STORAGE  [initandlisten] WARNING: the collection 'dp.aedm_advertis' lacks a unique index on _id. This index is needed for replication to function properly
2016-08-13T06:57:37.810+0800 I STORAGE  [initandlisten]     To fix this, you need to create a unique index on _id. See http://dochub.mongodb.org/core/build-replica-set-indexes
2016-08-13T06:57:37.810+0800 I STORAGE  [initandlisten] WARNING: the collection 'dp.aedm_campaign' lacks a unique index on _id. This index is needed for replication to function properly
2016-08-13T06:57:37.810+0800 I STORAGE  [initandlisten]     To fix this, you need to create a unique index on _id. See http://dochub.mongodb.org/core/build-replica-set-indexes

开始以为在同步时，因为oplogSize不够，没有同步索引过来，但查询索引是有的。
后准备再修改oplogSize   后再同步一次呢。但取消 oplogSize  大小后，再重启 mongod ,再登录 后发现问题好了。具体原因还有待再分析 了。