Unable to start MongoDB 3.0.2 service on CentOS 7

We are setting up a MongoDB server for the production environment on Amazon EC2 instance, but could not able to start the service. I've followed this documentation for setup. Here are the steps, I've taken for setting up the server:

Added following to `/etc/yum.repos.d/mongodb-org-3.0.repo`

[mongodb-org-3.0]

name=MongoDB Repository

baseurl=http://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/3.0/x86_64/

gpgcheck=0

enabled=1

And installed MongoDB 3.0.2 using `sudo yum install -y mongodb-org-3.0.2`

Created three partitions for data, journal & log:

sudo mkdir /mongo

sudo mkdir /mongo/data

sudo mkdir /mongo/log

sudo mkdir /mongo/journal

Created file system for three separate partitions:

sudo mkfs.ext4 /dev/xvdb

sudo mkfs.ext4 /dev/xvdc

sudo mkfs.ext4 /dev/xvdd

Created entry in `fstab` for reboot:

echo '/dev/xvdb /mongo/data ext4 defaults,auto,noatime,noexec 0 0

/dev/xvdc /mongo/journal ext4 defaults,auto,noatime,noexec 0 0

/dev/xvdd /mongo/log ext4 defaults,auto,noatime,noexec 0 0' | sudo tee -a /etc/fstab

And mounted the partitions:

sudo mount /mongo/data

sudo mount /mongo/journal

sudo mount /mongo/log

Given the permissions and created link

sudo chown mongod:mongod /mongo/data /mongo/journal /mongo/log

sudo ln -s /mongo/journal /mongo/data/journal

Configured `ulimit` & read ahead settings as given in the documentation link above. Verified permissions and partitions:

[deployer@prod-mongo ~]$ df -h

Filesystem      Size  Used Avail Use% Mounted on

/dev/xvda1      8.0G  1.3G  6.8G  16% /

devtmpfs        3.6G     0  3.6G   0% /dev

tmpfs           3.5G     0  3.5G   0% /dev/shm

tmpfs           3.5G   57M  3.4G   2% /run

tmpfs           3.5G     0  3.5G   0% /sys/fs/cgroup

/dev/xvdc       7.8G   36M  7.3G   1% /mongo/journal

/dev/xvdb       150G   51M  149G   1% /mongo/data

/dev/xvdd       3.9G   16M  3.6G   1% /mongo/log

Permissions:

[deployer@prod-mongo ~]$ ll /

total 32

lrwxrwxrwx.   1 root   root      7 Sep 29  2014 bin -> usr/bin

dr-xr-xr-x.   4 root   root   4096 Sep 29  2014 boot

drwxr-xr-x.  17 root   root   2860 May 11 12:11 dev

lrwxrwxrwx.   1 root   root      7 Sep 29  2014 lib -> usr/lib

lrwxrwxrwx.   1 root   root      9 Sep 29  2014 lib64 -> usr/lib64

drwxr-xr-x.   2 root   root      6 Jun 10  2014 mnt

drwxr-xr-x.   5 mongod mongod   41 May 11 05:06 mongo

drwxr-xr-x.  21 root   root    660 May 11 12:47 run

lrwxrwxrwx.   1 root   root      8 Sep 29  2014 sbin -> usr/sbin

Inside `/mongo`

[deployer@prod-mongo ~]$ ll /mongo/

total 12

drwxr-xr-x. 3 mongod mongod 4096 May 11 07:33 data

drwxr-xr-x. 3 mongod mongod 4096 May 11 07:31 journal

drwxr-xr-x. 3 mongod mongod 4096 May 11 08:58 log

After changing the configurations inside `/etc/mongodb.conf`

logpath=/mongo/log/mongod.log

dbpath=/mongo/data

Also, changed the SELinux setting to `permissive`. Now when I'm doing: `sudo service mongod start`, I'm getting this error:

Starting mongod (via systemctl): Job for mongod.service failed. See 'systemctl status mongod.service' and 'journalctl -xn' for details.
[FAILED]

Further logging:

[deployer@prod-mongo ~]$ sudo systemctl status mongod.service

mongod.service - SYSV: Mongo is a scalable, document-oriented database.
Loaded: loaded (/etc/rc.d/init.d/mongod)
Active: failed (Result: exit-code) since Tue 2015-05-12 04:42:10 UTC; 42s ago
Process: 22881 ExecStart=/etc/rc.d/init.d/mongod start (code=exited, status=1/FAILURE)

May 11 04:42:10 ip-xx-xx-xx-xx.local runuser[22887]: pam_unix(runuser:session): session opened for user mongod by (uid=0)
May 11 04:42:10 ip-xx-xx-xx-xx.localdomain runuser[22887]: pam_unix(runuser:session): session closed for user mongod
May 11 04:42:10 ip-xx-xx-xx-xx.local mongod[22881]: Starting mongod: [FAILED]
May 11 04:42:10 ip-xx-xx-xx-xx.local systemd[1]: mongod.service: control process exited, code=exited status=1
May 11 04:42:10 ip-xx-xx-xx-xx.local systemd[1]: Failed to start SYSV: Mongo is a scalable, document-oriented database..
May 11 04:42:10 ip-xx-xx-xx-xx.local systemd[1]: Unit mongod.service entered failed state.

Kernal version from uname -a:

3.10.0-229.1.2.el7.x86_64

If I directly run the mongodb service from the normal user something like this: sudo mongod --config /etc/mongod.conf, then this service is starting properly but not as the system service?

I've followed various articles and blog posts and stackexchange answers, but didn't get any solution.

http://stackoverflow.com/questions/30182016/unable-to-start-mongodb-3-0-2-service-on-centos-7