Move directory from one petition/device to another

[Cameron Beattie]

> On Fri, 2005-09-16 at 18:25, Cameron Beattie wrote:
>> > Had you picked almost any other directory, there'd have probably been
>> > no
>> > problem in doing so...
>> >
>> > However, /etc is necessary very early in the boot process. (i.e. before
>> > all the mounts are done.) Things like /etc, /bin, /sbin, /var need to
>> > be
>> > in the root so that they can be used during the boot. Other things,
>> > like
>> > /usr, /tmp, /opt can be moved into other partitions or devices /
>> > filesystems, and can be set up in /etc/fstab to be mounted during the
>> > boot
>> > process, without any harm to the system.
>> >
>> > Doing so is just a matter of mounting the new filesystem at a
>> > convenient
>> > mount point, cloning the directory structure over to it (tar is useful
>> > for
>> > this), getting into single user mode, deleting the original files and
>> > then
>> > mounting the new filesystem over the old directory as a mountpoint.
>> >
>> This is where I'm a bit lost. I have replicated the directory /etc as
>> follows:
>> mkdir /newetc
>> mount -t ext3 /dev/sda2 /newetc
>> cd /
>> tar cf - ./etc | (cd /newetc; tar xf -)
>>
>> How do I now convince the system to look in /dev/sda2/newetc/etc rather
>> than
>> /dev/sdb1/etc when I do a cd /etc?
>
> Errr....  You did read the part above that you quoted above noting
> that /etc was a special case that needs to be on the / partition
> didn't you?    The way you make your new partition appear at a
> certain directory is to mount it there.  You might unmount it
> from it's /newetc mount point and remount on /etc _but_ the
> way the system determines what to mount at bootup is to
> read /etc/fstab.  Notice the problem yet?  What you are
> doing would work with /home, /var or about anything else.
> Your next step would be to set up the /etc/fstab entry,
> rename the old directory (so you can delete the contents
> later), make a new empty one for the mount point, and
> reboot.
I did read it and I understood it to be difficult but not impossible. So I'm
now attempting to do the difficult and failing!

If I follow what you say (and I'm not sure I do), I would do the following 
(having copied the contents of /etc to /newetc):
vi /etc/fstab
/dev/sda2 /etc ext3 defaults 0 0

mv /etc /oldetc
mv /newetc /etc
reboot
>
> The contents of /etc are typically not all that big.  Why
> do you want it on a separate partition anyway?
I probably should have told the whole story. What I have is a bunch on
directories on a RAID5 array and want to move all the system-type ones e.g.
/etc /bin /sbin/ to a RAID1 array, leaving /home /usr etc where they are. I
guess it would be easier the other way around but that's not an option.

Any further advice would be appreciated.

Regards

Cameron