Antony wrote:
I have a Debian system on really small Flash memory like an embed system. A hard drive is mounted onto the system. I want to add more processes to the system like mail server. But the problem is /usr, /var, /etc are running out of space on the Flash memory. I'm planning to do the following:- make /usr, /var, /etc, /home directories on the mounted hard drive.- copy /usr, /var, /etc, /home original directories to new created directories.- edit /etc/fstab to mount these directories to new created locations. - remove the old /usr, /var, /etc, /home directories. Is that unsafe to do so?Do files in these directories being accessed before mounting from /etc/fstab?
Antony,As I see it, there should be no issues at all with your plan. It is true that /etc needs to be accessed 100% of the time, however, if you copied /etc to a new / location, edited /etc/fstab to reflect the new file locations for your new tree structure, then issued mount -a or perhaps mount -a -o remount, rw (I confess I have not done this for /, see man mount) but I think mount -a will work just fine. /etc is not special in any way, just before the mount -a it will path to your usb drive and after (unless you make a mistake in fstab) it will path to your new tree structure. Since all the files are the same, the running kernel will not see any difference and your running process should not see any difference.
I just don't see the concern others have posted about moving /etc, perhaps there is an error on my understanding that needs to be cleared up? What is the difference between doing this and say untaring your backup or doing a chroot (which now points to a different file structure)? Now if you have a mistake in fstab, I see bad things happening that might require a recovery boot to fix.
I am awaiting the results to increase my understanding. HTH -- Damon L. Chesser damon@damtek.com http://www.linkedin.com/in/dchesser