Repartition disk and reimport the whole system

Question

Hi everyone,
I have a working Arch Install and I love it. The only problem is that I need to repartition my HDD. The partition scheme is just slightly different. One partition that is now logical will be primary and most partitions (except one) will be slightly larger but that's it.
Meanwhile I need to reinstall Windows (I have a dual boot), then "copy/paste" my whole Arch system back and reinstall GRUB. For now I can think of a few problems.
1) If I reinstall GRUB from a live CD (would it work with Arch's install CD ?), will pacman still handle updates for it ?
2a) A friend advised me to use rsync to copy ALL of my system to an external HDD (I have JFS and ext2/3 partitions) and then use rsync again to recover my system (I was thinking of using a JFS external hard drive). Is it a good idea ? Will this keep all the needed metadata (privileges and such) ? Will it preserve symlinks ? hardlinks ?
2b) Is rsyncing really better than just copy-pasting all files ?
3) I guess I'll have to change my /etc/fstab once I have repartitioned, are there any other files to edit when I have my new partition scheme ?
4) How can I check that nothing has been broken/corrupted in the process ?
Are there "better"/alternative ways to do what I want (Repartition disk, reinstall Windows and get back my whole Arch system) ? What other problems could I encounter ?
Thank you in advance for your answers and sorry for my English (it is not my first language).

Answer 1

yms wrote:1) If I reinstall GRUB from a live CD (would it work with Arch's install CD ?), will pacman still handle updates for it ?
Should be fine. Grub doesn't change that often, and I don't think I've ever needed to re-do grub-install because of an update.
yms wrote:2a) A friend advised me to use rsync to copy ALL of my system to an external HDD (I have JFS and ext2/3 partitions) and then use rsync again to recover my system (I was thinking of using a JFS external hard drive). Is it a good idea ? Will this keep all the needed metadata (privileges and such) ? Will it preserve symlinks ? hardlinks ?
Yes, yes, and yes. However, so will cp -a. If you're just using an external drive attached to your local system to do this, cp -a should be fine.
yms wrote:2b) Is rsyncing really better than just copy-pasting all files ?
If you're copying to a separate machine over a network, I prefer rsync. It's easier than net-mounting the target drive and then copying to it, and network filesystems have a way of sometimes mangling ownership & permissions, depending what your setup is. This doesn't apply in your case though.
One caution about just copy&pasting your filesystem (not sure if this still applies with current udev, actually) -- you can't boot with a totally empty /dev. Copying all of the device entries from a booted, mounted /dev/ into your backup and then copying them back works fine, but it's probably better to do this:
mount -o bind / /mnt/temp-root
cp -a /mnt/temp-root/dev /your-backup-root/dev
umount /mnt/temp-root
That'll give you the device entries that are actually in your root filesystem's /dev, before /dev gets mounted on top of it.
yms wrote:3) I guess I'll have to change my /etc/fstab once I have repartitioned, are there any other files to edit when I have my new partition scheme ?
crypttab, if you have any encrypted partitions. /etc/suspend.conf if you're using userspace suspend (it'll need to know the new swap partition to resume from after s2disk). mdadm.conf if you have software RAID and are using that. Likewise for stuff in /etc/lvm (possibly).
yms wrote:4) How can I check that nothing has been broken/corrupted in the process ?
On your current system:
find / -type f -print0 | xargs -0 md5sum >> /big-file-checksum-list
When you've got everything copied back:
find / -type f -print0 | xargs -0 md5sum >> /big-file-checksum-list2
Then sort those two files and compare them.
yms wrote:Are there "better"/alternative ways to do what I want (Repartition disk, reinstall Windows and get back my whole Arch system) ? What other problems could I encounter ?
Some things I ran into while installing Windows 7:
- Win7 has a separate 100MB boot partition. As far as I know, it's not easy to pick an existing partition and tell it, "this is your boot partition." I just let the installer create it for me.
- Win7 does not obey some partition table conventions -- I can't edit my partition table with cfdisk because Windows 7 apparently got some disk geometry slightly wrong (You know that 8mb of free space that XP & NT used to leave at the end of disks? I don't think they've fixed that yet). fdisk, parted, and sfdisk are all OK though.
Edit: one of the Win7 problems turned out to be something else; removed it.
Last edited by thetrivialstuff (2009-11-04 19:34:27)