installer crashed. tried installing on an existing, but empty, btrfs

[Rolf Rander Næss]

setup:
 - two ssd (Corsair CSSD-F120GB2)
 - each have two partitions: 100M for efi (on hda) and boot (on hdb) and the rest as two parts of btrfs
 - partitioned with gparted and created btrfs before starting installation
 - installer crashed

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: ubiquity 2.12.16
ProcVersionSignature: Ubuntu 3.5.0-17.28-generic 3.5.5
Uname: Linux 3.5.0-17-generic x86_64
ApportVersion: 2.6.1-0ubuntu3
Architecture: amd64
CasperVersion: 1.328
Date: Mon Nov 19 23:57:36 2012
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi.signed file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash --
LiveMediaBuild: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
ProcEnviron:
 TERM=unknown
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Rolf Rander Næss (rolf-ness)]

Might be a duplicate of Bug #1078363. Both seems to have crashed at the sape spot in pluginstall.py

[Rolf Rander Næss (rolf-ness)]

it seems mapdevfs (or grub-installer, depending on your point of view, i guess) can't handle filesystems spanned across several devices. (I also can't figure what mapdevfs is supposed to do, in my tests, it just returns its own input)

Workaround was to set up btrfs on one disk and add the second after install, followed by a btrfs fs balance.