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Re: Clone root partition

Digby Tarvin wrote:
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
	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!


On Sat, Dec 30, 2006 at 05:45:34PM +0000, T wrote:
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

  cp -a / /mnt/point

  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

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

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


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)

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Dear Digby and all,

Suppose I have a production server with a /dev/sda disk and I mount a second disk /dev/sdb in order to clon sda to sdb (booting from a live cd). Sdb is the disk from a backup server (similar to the production server) I want to use when the production server fails.

After doing "dd if=/dev/sda of=/dev/sdb bs=10k"...do I have to do something on /etc/fstab and /boot/grub/menu.lst from the second drive when this second disk is on the backup server ?? Or nothing else to do in the second disk is OK to start the backup server ???

Really thanks and happy new year !!!


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