This is how / should be mounted
mount
/dev/md0 on / type ext3 (rw,errors=remount-ro)
but in fact, it is mounted read-only because of unknown reason so far for me.
cat /proc/mounts
/dev/md0 / ext3 ro,relatime,errors=remount-ro,data=ordered 0 0
:/var/log# echo aaa > /tmp/ddd
bash: /tmp/ddd: Read-only file system
As ext3 has errors=remount-ro flag, the possible reason is that the filesystem has errors. When I checked syslog/messages/dmesg I did not find any related information (no disk failures, filesystem errors etc.). This server does not have any iLo or so.
So what do you recommend, how to recover the root filesystem without working physically on the server.
Update:
:/var/log# mount -o remount,rw /
mount: cannot remount block device /dev/md0 read-write, is write-protected