My Windows installation was on a 120 GB SSD and I decided it was time to upgrade that to 256 GB. Because I didn't want to reinstall my Windows, I copied it with CloneZilla. Everything seemed to work fine, until I formatted the old partition. Then the Windows partition stopped booting. I could access the files from ArchLinux. I tried to run some commands from the Windows Recovery Console, but I held it wrong and the result was that my Archlinux stopped booting too! Yaaay.
After lots of digging on various tutorials, I managed to put together the following to fix it. First, download a Live Linux Image to boot from an USB. I used the Antergos one, but it shouldn't matter much.
The extra fun for me was that for reasons my Archlinux harddisk is using LVM (I have no idea why I did that 3 years ago). So first, I had to load the LVM partitions:
vgchange -a y
Then I had to see the partitions with
Then I had to mount the needed partitions to the correct folders. In my case, for some reason, which I also don't remember, my /home folder was separate from the others, so I needed to mount it separately. The /mnt can be somewhere else and then you just chroot.
sudo su mount /dev/mapper/AntergosRoot /mnt mount /dev/sda1 /mnt/boot mount /dev/mapper/AntergosHome /mnt/home arch-chroot /mnt
The last step was to regenerate the grub config and install it:
grub-mkconfig -o /boot/grub/grub.cfg grub-install /dev/sda
And after this my Linux started working again (for some definition of working, because I think the Nvidia drivers are still screwing around). Time to fix my precious Windows 10 Insider Preview installation.
Download an install image of Windows, put it on a USB with Rufus and then get to the recovery console. You have to start diskpart and then run some commands inside it:
diskpart >sel disk 0 >list vol >sel vol 2 >assign letter=x: >exit
In diskpart, you have to look at your volumes and figure out which one is the Windows boot partition (it's a FAT32 partition, that is quite small, around 200 MB, and is marked as bootable I think). You then select that volume (number 2 in my case), assign it a drive letter and exit diskpart. You need the drive letter so that you can access the partition later.
You change directory to it and run the following command:
X: bcdboot C:\windows /s X: /f UEFI
Warning: the Windows partition might not be C! In my case it was E, but only in diskpart. The naming of partitions seems to be different here.
And after this, my Windows booted up too! No dataloss so far! Yaaaaay!