`grub-install` failed on a partitionless fully luks encrypted 4TB HDD

[Hamid Nassiby]

Hi
​​
,

I am trying to install grub (v. 2.02~beta2-22+deb8u1) on a partitionless
4TB HDD which is fully encrypted by luks. Over the luks, I have 3 logical
volumes (LVM2), one is
​for ​
swap,
​second for​

​/​
and the last one
​ for /​
home. I have a Debian Jessie 8.6 installed on the
​setup (in fact I moved an already existing installation to this new 4TB
HDD). I am able to boot into the installed system via a grub which is
installed on another HDD (sda which has the same version of grub and the
same version of Debian).

But I've not been able to install grub on this drive (which is /dev/sdb in
my setup).
I get the following lines:

 address@hidden:/# grub-install  --force /dev/sdb
>> Installing for i386-pc platform.
>> File descriptor 4 (/) leaked on vgs invocation. Parent PID 1920:
>> grub-install
>> File descriptor 4 (/) leaked on vgs invocation. Parent PID 1920:
>> grub-install
>> File descriptor 4 (/) leaked on vgs invocation. Parent PID 1920:
>> grub-install
>> File descriptor 7 (/) leaked on vgs invocation. Parent PID 1920:
>> grub-install
>> File descriptor 8 (/) leaked on vgs invocation. Parent PID 1920:
>> grub-install
>> grub-install: error: unable to identify a filesystem in
>> hostdisk//dev/sdb; safety check can't be performed.
>>
>
​If I try with -s flag:

address@hidden:/# grub-install  -s /dev/sdb
>> Installing for i386-pc platform.
>> File descriptor 4 (/) leaked on vgs invocation. Parent PID 4091:
>> grub-install
>> File descriptor 4 (/) leaked on vgs invocation. Parent PID 4091:
>> grub-install
>> File descriptor 4 (/) leaked on vgs invocation. Parent PID 4091:
>> grub-install
>> File descriptor 7 (/) leaked on vgs invocation. Parent PID 4091:
>> grub-install
>> File descriptor 8 (/) leaked on vgs invocation. Parent PID 4091:
>> grub-install
>> grub-install: warning: Attempting to install GRUB to a partitionless disk
>> or to a partition.  This is a BAD idea..
>> grub-install: error: embedding is not possible, but this is required for
>> RAID and LVM install.
>> ​
>
>
​I have​ put "GRUB_ENABLE_CRYPTODISK=y" in "/etc/default/grub" and my
grub.cfg entry is the same as the one on /dev/sda (which already has grub
installed on it. sda is a partitioned drive non-encrypted and non-lvm).

Any idea would be much appreciated,
Thanks in advance,
Hamid