today some guys are adding some luns from a SAN so in order to add them I followed this command
Alright lets start from the beginning. As per the above line I think what has happened is SAN guys added some LUNS which I will take it as device because LUNS on SAN is device for server like /dev/sda or /dev/sdb etc. You said that you issued the command to re-scan the LUN but now you are not able to write anything and the file system is mounted as read-only.
Now the above is not possible until and unless re-scanning mounted the file-system as read only. My only motive for running mount -a command was to remount the all the partitions using the options present in /etc/fstab but you said that none of the commands are working.
1. Let us know if they have increase the size of the existing LUNs or they added up new LUNs.
2. As far as I know adding up new LUNs shouldn't affect existing partitions.
3. mount commands should work. Is the document you are referring says anything about this.
I would still suggest a restart as without getting the commands to work I dont think we are going anywhere.