[techtalk] installing new hd

[Malcolm Tredinnick]

On Sat, Sep 02, 2000 at 06:22:54PM -0700, Allen Heinecke wrote:
> I am considering installing a new HD in my computer as the old one is
> running out of space... however the "partition" / location that is running
> out of space is root...
> 
> what is the best way to migrate all of the root files, including the
> bootup files to this new HD?

There are two situations you may be in here. I'll give some hints to
both and then others can flame me.

(A) You are wanting to completely replace the old HD with new one (the
more difficult solution).

	Hook up the new HD to your machine and use something like fdisk or
	disk druid to partition it as you like. Then mount each partition
	under an appropriate directory. For example, suppose the new disk
	will have partitions called '/', '/tmp' and '/usr' (as partitions 1,
	2 and 3), I would make directories under /mnt called 'root', 'tmp',
	'usr' and then use the commands..

		mount -t ext2 /dev/hdd1 /mnt/root
		mount -t ext2 /dev/hdd2 /mnt/tmp
		mount -t ext2 /dev/hdd3 /mnt/user
	
	Then copy everything from your current HD to the new home on the new
	HD. Note that you will not need to copy the contents of /proc (they
	are not real files).

	Adjust /mnt/root/etc/fstab to mount the new partitions in the right
	spots (bearing in mind, that after you swap the new for the old, it
	will be /dev/hdc, so you would mount /dev/hdc1 under /tmp in the
	above example).

	I _think_ you probably need to rerun LILO so that the kernel copy
	that is on the new drive understands where it lives. There may well
	be a way to do this at this point in the plan, but I can't work out
	how to get LILO to write the result to /dev/hdd's MBR in a way that
	will work when you reboot it as /dev/hdc. Somebody else may be able
	to solve this (please?). Instead, I propose a different plan in the
	next paragraph.

	Shutdown the machine, put the new HD in place of the old one and
	reboot using a boot floppy (if you don't have one of these, or can't
	create one, ask again on this list and I, or somebody else, will try
	to help). Run /sbin/lilo on the new HD and it should correctly alter
	the bootup information.

** Caveat Emptor: What I have described is completely untested!!
However, it looks like it will work. Whatever you do, don't do anything
destructive to the old HD until you are sure the swapover worked.
Alternatively, go with plan B (below)...

(B) You want to add in the second HD to the system, but will keep the
first on installed as well (much easier!).

	Partition the new HD as you like and make each partition a "major"
	part of the directory structure, like /usr/local or /tmp or /usr or
	whatever. For the time being, mount these new partitions under
	appropriate directories under /mnt (e.g. /mnt/usr/local) using the
	mount commands I gave above.

	Copy everything from the current /usr directory over to what will be
	the new /usr directory (just an example). So in this example, you do
	something like

		cp -r /usr/ /mnt/usr
	
	Do this for all the directories you want to move across.

	**NOTE: You should leave your kernel image (probably in /boot, so
	leave all of /boot), /etc, /bin and /sbin on the first harddrive,
	otherwise you will have trouble booting!

	Now alter /etc/fstab to mount the new partitions under their new
	directory names. So, for example, if the partition mounted as
	/mnt/usr in the above case is /dev/hdd3, you would add a line to
	/etc/fstab like

		/dev/hdd3	/usr	ext2	defaults	1 2
	
	You can now reboot and verify that the new partition was mounted
	under the right spot.

	To reclaim your disk space, remove the above line from fstab,
	reboot again (this puts the old /usr directory back) and then
	remove all the contents of /usr (which frees up space on the
	first HD). Finally, add the fstab line back and reboot again.
	What could be easier?

OK .. both these methods look pretty involved on the screen, but I have
used the second one successfully. For extra safety, you may wish to wait
a couple of days and see how many people call me an idiot on this list
(or just point out blatant errors I've made).

I hope I've been clear enough without being too verbose, if you need
more information, just holler. :)

Cheers,
Malcolm

-- 
Malcolm Tredinnick            email: malcolm at commsecure.com.au
CommSecure Pty Ltd
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