read only to read-and-write filesystem

Remount as read-write a read only file-system.

( Is common for VMs with full virtual disks to come up with their user-space file-systems mount as ro (read-only). )

Check where the root or the file-system that you want to mount as read-write(rw) is mounted.
# mount
/dev/sda1 on / type ext3 (rw)

/proc/mounts and the mount command may report rw even if the file-system is mounted as ro.

Remount root as read-write.
# mount -o remount,rw /dev/sda1 /

Remount as read-write a filesystem in linux