官方安装手册

http://docs.mongodb.org/manual/tutorial/install-mongodb-on-red-hat/

安装完成后，登录出现如下告警：

1.登录mongo shell

[root@localhost ~]# mongo

缺少openssl、libssh3

yum -y install openssl
service mongod restart

2.I use mongodb 3.0 and find a warning:

[root@localhost ~]# mongo
MongoDB shell version: 3.0.1
connecting to: test
Server has startup warnings: 
2015-03-13T16:28:29.405+0800 I CONTROL  [initandlisten] 
2015-03-13T16:28:29.406+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2015-03-13T16:28:29.406+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2015-03-13T16:28:29.406+0800 I CONTROL  [initandlisten] 
2015-03-13T16:28:29.407+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2015-03-13T16:28:29.407+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2015-03-13T16:28:29.407+0800 I CONTROL  [initandlisten]

solved:

vi /etc/init.d/mongod
#行首添加
if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
  echo never > /sys/kernel/mm/transparent_hugepage/enabled
fi
if test -f /sys/kernel/mm/transparent_hugepage/defrag; then
   echo never > /sys/kernel/mm/transparent_hugepage/defrag
fi

重启mongod
service mongod restart

3.Recommended ulimit Settings

Every deployment may have unique requirements and settings; however, the following thresholds and settings are particularly important for mongod and mongos deployments:

-f (file size): unlimited

-t (cpu time): unlimited

-v (virtual memory): unlimited [1]

-n (open files): 64000

-m (memory size): unlimited [1] [2]

-u (processes/threads): 64000

Always remember to restart your mongod and mongos instances after changing the ulimit settings to ensure that the changes take effect.

vi /etc/profile

在最后添加

ulimit -n 64000

ulimit -u 64000

source /etc/profile

2015-04-02T01:36:21.150-0700 I CONTROL  [initandlisten] 
2015-04-02T01:36:21.150-0700 I CONTROL  [initandlisten] ** WARNING: soft rlimits too low. rlimits set to 1024 processes, 64000 files. Number of processes should be at least 32000 : 0.5 times number of files.