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I'm looking to have root on a RAID BtrFS built on a number of luks disks. I typically do this on Debian or Ubuntu by preparing my disks before-hand, then running the install into those disks. At the end, I need to pivot into the new system to modify crypttab and fstab.

I'm trying the same thing with Qubes, which uses the Anaconda installer. When I get to the GUI partitioner, the BtrFS appears under the "Unknown" dropdown, but if I try to set "mount point to "/" and then "Update Settings," it errors with "You must create a new filesystem on the root device." (But there is already one there.) If I use "+" instead, I am told "Not enough free space for thin provisioning." The installer is clearly confused about how much space is available: "Available space 992.5 KiB," "Total space 238.47 GiB." In fact, there is 932.35GiB in the RAID'ed BtrFS.

If I just open the luks devices, but put no FS in there, then all /dev/mapper/luks* devices appear in the partitioner under the "Unknown" dropdown, but choosing "New mount points will use the following partitioning scheme: Btrfs," none of the devices allow me to associate a mount point. It's greyed out, or if I try to use "+" and test it with a single disk, it comes back with an error "Not enough disks for single." (But I have multiple LUKS disks there!)

Trying without any prior formatting, neither luks nor Btrfs, I find that the partitioner can't handle bare disks. It wants a partition table (which I don't).

Does anyone have a way through this?

Edit: It appears there are serious issues with this installer.

Diagon
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1 Answers1

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The answer to all of this appears to be: "Don't try to fight the Anaconda, as you will lose." Despite the access to a root terminal (Control-Alt-F1 reaches a tmux session, Control-b 2, reaches a terminal with root privileges), you must return to the graphical installer, which is too limited to allow any headway, particularly with BtrFS disks. Anaconda sees BtrFS not as a filesystem, but as a device, and this makes problems insurmountable.

The solution is to do a dummy install and then modify all disks, editing crypttab, fstab, /etc/default/grub as needed. Then pivot in and run dracut -f, along with grub2-mkinstall if needed. Also, if necessary, grub2-install.

One advantage of BtrFS in this process, is that it's possible to avoid having to use a live-DVD or Anaconda's rescue shell to make changes in a system "at rest", afterward pivoting in to run dracut et al. You'd just use btrfs device add to add a device to the root, and then btrfs device remove the original. Then make relevant changes to the original partitions, afterwards reversing the add/remove. So it's possible to make changes by moving back and forth from one disk to the other.

Diagon
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