On 18 April 2016 at 23:06, David Alcorn <nroclaed@xxxxxxxxx> wrote: > Nicolas: > > My flash drive uses BTRFS and I am comfortable with your instructions > with one exception. What does "update /etc/default/grub" mean? > > Currently, I am waiting for a scrub to verify that all is in good > order before fixing the problem. I meant that more as a general precaution and good habit. The most common check/change would be to make sure the "resume=foo" option matches the UUID or /dev/sdX of the swap partition; it's mostly relevant to laptop users. More to the point, as Austin and Chris mentioned the tricky bit is going to get GRUB to boot from raid6 profile btrfs if your /boot is part of your btrfs volume. I honestly don't know if it will work... Do you have a separate /boot partition? What is your /dev/sda being used for? UEFI firmware loads GRUB's EFI payload, which loads the different stages of grub that allow file system access, which is necessary for grub to be able to find the kernel. The EFI payload is installed to your FAT-formatted ESP partition, which is usually mounted to /boot/grub/efi/EFI. I also suspect that without a separate /boot partition GRUB won't be able to find the kernel (/boot/vmlinuz-4.4.0-1-amd64). If I remember correctly GRUB's stage1 talks to your motherboard's firmware, stage2 enables filesystem access (/boot/grub/x86_64-efi/btrfs.mod), and stage3 loads the kernel. En bref, if GRUB has insufficient support for btrfs' raid6 profile then grub will either be unable to access btrfs.mod, or btrfs.mod will be unable to enable access /boot/vmlinuz-4.4.0-1-amd64. I suspect the following worst-case scenario if you don't have a partition you can use for /boot, and didn't leave any unallocated space on any of your drives, and if you can't shrink something like a swap partition to make room for /boot: No need to backup/restore if you have a usb port to dedicate to /boot. A more exotic solution would be using a small SATADOM to hold it, but then you lose a SATA port ;-) After sending the rootfs of your USB flash installation to a subvolume of your raid6, you can manually use the GRUB command line on your existing USB stick to attempt to boot the rootfs subvolume of your raid6. Cheers, Nicholas -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
