Moving a root directory to a separate partition

Question

I'd like to create a new partition and move the contents of the /var directory to it for the security reason of having /var/www and other subdirectories "mounted" with nosuid, noexec, and nodev permissions. How do I do it for /var or any other root directory?

Answer 1

Actually, a slight modification to warl0ck's plan (because I'm paranoid)

1. create the new partition
2. boot to single-user mode
3. mount the new partition as /new_var or something, and rsync as described
   • you might as well run aptitude autoclean before running rsync, to reduce the amount getting copied over (or even ... clean if you don't mind re-downloading your apt cache)

4. move /var to /old_var so you don't lose it right away, and then mount the new partition as /var

   • there may be live logs or pid files in old_var - if you don't mind losing whatever changed since re-starting, you can ignore those

5. edit fstab so the new partition will mount as /var on future boots, and reboot to normal multi-user mode

6. if all that went well, you can sudo rm -fr /old_var when you're sure it's working. If anything breaks, you still have old_var around

Answer 2

A simple way is mount the new partition on some temporarily location, then do a rsync to synchronize /var/ and the new location,

Afterwards, boot to root maintain mode, erase /var, and change fstab that mount the new partition onto /var