Unable to start mongod service - mongodb

Question

I installed mongodb using the information in this link. However, when I user the service mongod start command I get the following error. Can someone help me troubleshoot?
[Piyush#localhost ~]$ service mongod start
/etc/init.d/mongod: line 54: ulimit: open files: cannot modify limit: Operation not permitted
/etc/init.d/mongod: line 56: ulimit: max user processes: cannot modify limit: Operation not permitted
Starting mongod: runuser: using restricted shell /bin/false
runuser: cannot set groups: Operation not permitted
[FAILED]
[Piyush#localhost ~]$ sudo service mongod start
[sudo] password for Piyush:
Starting mongod: [FAILED]
I tried using --repair command. I get the following output for that:
[Piyush#localhost ~]$ sudo mongod --repair
2014-09-24T00:05:06.089-0400 [initandlisten] MongoDB starting : pid=2807 port=27017 dbpath=/data/db 64-bit host=localhost.localdomain
2014-09-24T00:05:06.089-0400 [initandlisten] db version v2.6.4
2014-09-24T00:05:06.089-0400 [initandlisten] git version: 3a830be0eb92d772aa855ebb711ac91d658ee910
2014-09-24T00:05:06.089-0400 [initandlisten] build info: Linux build7.nj1.10gen.cc 2.6.32-431.3.1.el6.x86_64 #1 SMP Fri Jan 3 21:39:27 UTC 2014 x86_64 BOOST_LIB_VERSION=1_49
2014-09-24T00:05:06.089-0400 [initandlisten] allocator: tcmalloc
2014-09-24T00:05:06.090-0400 [initandlisten] options: { repair: true }
2014-09-24T00:05:06.106-0400 [initandlisten] finished checking dbs
2014-09-24T00:05:06.106-0400 [initandlisten] dbexit:
2014-09-24T00:05:06.106-0400 [initandlisten] shutdown: going to close listening sockets...
2014-09-24T00:05:06.106-0400 [initandlisten] shutdown: going to flush diaglog...
2014-09-24T00:05:06.106-0400 [initandlisten] shutdown: going to close sockets...
2014-09-24T00:05:06.106-0400 [initandlisten] shutdown: waiting for fs preallocator...
2014-09-24T00:05:06.106-0400 [initandlisten] shutdown: closing all files...
2014-09-24T00:05:06.106-0400 [initandlisten] closeAllFiles() finished
2014-09-24T00:05:06.107-0400 [initandlisten] shutdown: removing fs lock...
2014-09-24T00:05:06.107-0400 [initandlisten] dbexit: really exiting now
[EDIT 1]_____________________________________________________________________________
In the log file I see:
[root#localhost ~]# cat /var/log/mongodb/mongod.log.2014-09-24T16-00-32
2014-09-24T11:54:23.636-0400 ***** SERVER RESTARTED *****
2014-09-24T11:54:23.665-0400 [initandlisten] MongoDB starting : pid=3004 port=27017 dbpath=/var/lib/mongo 64-bit host=localhost.localdomain
2014-09-24T11:54:23.665-0400 [initandlisten] db version v2.6.4
2014-09-24T11:54:23.665-0400 [initandlisten] git version: 3a830be0eb92d772aa855ebb711ac91d658ee910
2014-09-24T11:54:23.665-0400 [initandlisten] build info: Linux build7.nj1.10gen.cc 2.6.32-431.3.1.el6.x86_64 #1 SMP Fri Jan 3 21:39:27 UTC 2014 x86_64 BOOST_LIB_VERSION=1_49
2014-09-24T11:54:23.665-0400 [initandlisten] allocator: tcmalloc
2014-09-24T11:54:23.665-0400 [initandlisten] options: { config: "/etc/mongod.conf", net: { bindIp: "127.0.0.1" }, processManagement: { fork: true, pidFilePath: "/var/run/mongodb/mongod.pid" }, storage: { dbPath: "/var/lib/mongo" }, systemLog: { destination: "file", logAppend: true, path: "/var/log/mongodb/mongod.log" } }
2014-09-24T11:54:23.680-0400 [initandlisten] journal dir=/var/lib/mongo/journal
2014-09-24T11:54:23.680-0400 [initandlisten] recover : no journal files present, no recovery needed
2014-09-24T11:54:23.680-0400 [initandlisten]
2014-09-24T11:54:23.680-0400 [initandlisten] ERROR: Insufficient free space for journal files
2014-09-24T11:54:23.680-0400 [initandlisten] Please make at least 3379MB available in /var/lib/mongo/journal or use --smallfiles
2014-09-24T11:54:23.680-0400 [initandlisten]
2014-09-24T11:54:23.681-0400 [initandlisten] exception in initAndListen: 15926 Insufficient free space for journals, terminating
2014-09-24T11:54:23.681-0400 [initandlisten] dbexit:
2014-09-24T11:54:23.681-0400 [initandlisten] shutdown: going to close listening sockets...
2014-09-24T11:54:23.681-0400 [initandlisten] shutdown: going to flush diaglog...
2014-09-24T11:54:23.681-0400 [initandlisten] shutdown: going to close sockets...
2014-09-24T11:54:23.681-0400 [initandlisten] shutdown: waiting for fs preallocator...
2014-09-24T11:54:23.681-0400 [initandlisten] shutdown: lock for final commit...
2014-09-24T11:54:23.681-0400 [initandlisten] shutdown: final commit...
2014-09-24T11:54:23.681-0400 [initandlisten] shutdown: closing all files...
2014-09-24T11:54:23.681-0400 [initandlisten] closeAllFiles() finished
2014-09-24T11:54:23.681-0400 [initandlisten] journalCleanup...
2014-09-24T11:54:23.681-0400 [initandlisten] removeJournalFiles
2014-09-24T11:54:23.684-0400 [initandlisten] shutdown: removing fs lock...
2014-09-24T11:54:23.684-0400 [initandlisten] dbexit: really exiting now

Answer 1

The --repair flag is meant to repair a corrupt database, not to solve any permission problems
You obviously didn't follow the instructions of the link too closely, because he did start the service as root. ;) sudo may only allow certain parts of the init scripts to be executed with superuser rights by the user calling it. Others may (though they shouldn't) silently fail. As for init scripts at least: sudo != being root.
To fix the problem: sudo chown mongod -R /var/log/mongodb/ && sudo chown mongod -R /var/run/mongodb && sudo chown mongod -R /var/lib/mongo Then become root and try to run mongo manually with sudo -u mongod mongod --dbpath /var/lib/mongo --logpath /var/log/mongodb/mongod.log. In case there are other problems left, mongodb will tell you. Fix those until starting mongodb manually as written above works flawless, then use the initscript from that point on.
Edit: corrected the --dbpath option as per comment