I did this only yesterday - but in my case I wanted a mirror
image of the entire system, not just the root partition.
The simplest most bullet proof procedure I could come up with was:
1. dd if=/dev/hda of=/dev/sda
2. vi /etc/fstab in the copy and 1,$s/hda/sda/
3. either
a. edit /boot/grub/menu.lst on the internal drive
to add a boot obtion passing the USB root to the kernel
or
b. if your host supports USB booting, update the boot sector
on sda to look for the stage 2 boot in the USB partition.
I used for first option, so am not sure if I have covered everything
required for a direct USB boot...
I booted using the USB copy and everything looked to be working fine.
Didn't use 'sync,noerror' in the dd operation because I count on having
perfect media, and if I don't I want to know about it!
Regards,
DigbyT
On Sat, Dec 30, 2006 at 05:45:34PM +0000, T wrote:
> Hi,
>
> I'm trying to compile a comprehensive document on cloning root partitions.
> My immediate goal is to clone my current working Linux to external USB HD,
> so that I can use it wherever I go.
>
> By comprehensive I mean it should not be as simple minded as
>
> dd if=/dev/hda2 of=/dev/sda2
>
> or
>
> cp -a / /mnt/point
>
> or
>
> tar -p -m cf - / | (cd /mnt/point; tar xf - )
>
> I know they work, but there are so many things have been left out. By
> comprehensive, I mean I want to know all relevant things that need to be
> considered.
>
> For example for dd, let alone its rigid limitation, if you use it, at least
> the 'conv=sync,noerror bs=4k' options should be used: sync,noerror just
> means continue and zero fill any error blocks, bs=4k just writes 4k at a
> time which will speed things up a lot. For cp, at least 'cp -ax' should be
> used.
>
> But there are still much more to it.
>
> First, directories that don't need to copy over, like /tmp, /proc. With
> modern Linux that uses udev, the /dev and /sys don't need to be copied
> either. Anything else (besides distro specifics like /var/cache/apt/archives)?
>
> 2nd, the clone partition should be made bootable, by grub or lilo.
>
> Anything else? Like the concerns of /etc/fstab...
>
> Last, with all the above concerns, how to achieve them with various tools?
>
> Keywords: tar rsync find cpio dd
>
> thanks
>
> PS. If you come across this message late, be it a week or even a month
> late, please do comment, I hope this thread can be a one stop place for
> people looking for concerns over cloning root partitions.
>
>
> --
> Tong (remove underscore(s) to reply)
> http://xpt.sourceforge.net/
>
>
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