I’m upgrading a server again and we replaced the RAID array with SSDs (it’s a 10x IOPS improvement; so worth it). But booting the system it fails to start because the old UUID listed in /etc/fstab is no longer available.
That “Unable to resolve” message caused the filesystem check to fail. Linux drops into a shell with the root volume loaded but in read-only mode.
To fix this I needed to change /etc/fstab to remove the offending entry. But I couldn’t write to the file system.
The obvious solution (with help from our hosting partner) is to remount the root partition as read-write:
mount -o remount,rw /
Now, I can edit /etc/fstab, comment out the offending line, exit and the system will reboot into a running server.
Jeremy Wadsack 