# echo 1 > /file
-bash: /file: Read-only file system 
# mount
/dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw)
# mount -o remount,rw /
mount: block device /dev/VolGroup00/LogVol00 is write-protected,mounting read-only

我可以在没有重启服务器的情