I have setup a Debian vm to boot with a RAID1 btrfs made with two encrypted devices. I had setup the vm like this
/etc/default/grub
GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_ENABLE_CRYPTODISK=y
GRUB_CMDLINE_LINUX_DEFAULT="quiet"
GRUB_CMDLINE_LINUX="cryptdevice=UUID=b5259968-2f96-4a45-87bf-c658f6d0f55d:luksvda4 cryptdevice=UUID=6aae0722-1fc0-49d1-85d7-ca5668b06683:luksvdb4 rootflags=degraded"
GRUB_TERMINAL="console"
This is the /etc/fstab
LABEL=ROOT / btrfs defaults,degraded 0 1
LABEL=BOOT /boot ext4 defaults 0 2
LABEL=SWAP none swap sw 0 0
this is the /etc/crypttab
# <target name> <source device> <key file> <options>
luksvda4 UUID=b5259968-2f96-4a45-87bf-c658f6d0f55d none luks
luksvdb4 UUID=6aae0722-1fc0-49d1-85d7-ca5668b06683 none luks
And finally the disk configuration
fdisk -l /dev/vda
/dev/vda1 48 65583 65536 32M BIOS boot
/dev/vda2 65584 2162735 2097152 1G Linux RAID
/dev/vda3 2162736 8454191 6291456 3G Linux swap
/dev/vda4 8454192 62914526 54460335 26G Linux filesystem
fdisk -l /dev/vdb
/dev/vdb1 48 65583 65536 32M BIOS boot
/dev/vdb2 65584 2162735 2097152 1G Linux RAID
/dev/vdb3 2162736 8454191 6291456 3G Linux swap
/dev/vdb4 8454192 62914526 54460335 26G Linux filesystem
I use the classical mdadm ext4, but also btrfs on boot partition(unencrypted of course) works fine. The system boot, no problem after asking the two password for the two luks devices. But when I remove the firs disk(simulating a fault) go to the initramfs console and I have to mount the disk manually(sic!), this not happen with the same configuration on Slackware. The question is: is possible to force Debian to boot when one of the two disk is not available?