Bug#720073: grub fails to install with root partition >~50GB
If GRUB installed successfully, and you booted it, it would then need to
load the kernel image and initramfs into memory. AFAIK it would be
unable to do that if those are inside of the encrypted LVM. (The wheezy
version of GRUB2 can't itself open the encrypted LVM, and the kernel
would be not running yet).
It is mentioned in the install guide but many people seem to miss this
> 220.127.116.11. Guided Partitioning
> If you choose guided partitioning using (encrypted) LVM, the installer will also create a separate /boot partition. The other partitions, including the swap partition, will be created inside the LVM partition.
> 18.104.22.168. Configuring Encrypted Volumes
> The only exception is the /boot partition which must remain unencrypted, because currently there is no way to load the kernel from an encrypted partition.
It is unfortunate the user is not warned of the problem until the final
stages of the install process... (similar situation to Bug#717511).
I'm not familiar with UEFI, but if the 'efiboot' partition is what I
think it is, it need only be about 1MiB. But you would also create for
example a 254MiB partition configured with a mountpoint of /boot. It
must also be of a filesystem recognised by GRUB; something simple like
ext2 should be ideal.
There can be issues with older BIOSes and partitions over a certain size
like you mention, but the configuration I described above fits
everything needed to boot the kernel within the first 256MiB of the disk.