I am looking for some experienced Linux guru to solve this problem. After rebooting server I keep getting message like this: Warning: session_start() [function.session-start]: open(/tmp/sess_f4d7708f2793f95b5f75437d44cb6e92, O_RDWR) failed: Read-only file system (30) in /home/account/public_html/domain.com/index.php on line 2 It looks like it's a problem with some permissions of tmp folder on the server. But I can't even delete (logged in as root) tmp files manually, like I have no access of root folder at all, and it looks like would be set to read only.
It sounds like a problem with the hard drive, and the operating system is going into read only so that it protects what is there. Have your data center run and fsck on the drive and see what it comes up with.
Looks like a failed Hard Drive as Chris mentioned above, if you have raid then just replace the bad one on the array, powering down and then powering on the server will work temporarily but i suggest you contact your hosting and tell them your hdd is failing.
I also believe it could be a hard drive issue. If you have a backup , try maybe first to change your hdd
This issue is fixed by me, turned out that the /tmp partition got corrupted, removed and recreated the partition and issue got resolved.