Re: Discarding improperly nested partition ?

[Jordan Uggla]

On Fri, Jan 27, 2012 at 12:57 AM, Sebastian Lemke [infoworxx]
<address@hidden> wrote:
> /usr/sbin/grub-probe: warn: Discarding improperly nested partition
> (hd0,gpt2,gpt4)
This means that grub is detecting that (hd0,gpt2) (the second gpt
partition on the first disk, or "sda2") contains a GPT label which
defines partitions (since sda2 is a partition itself, this is a
"nested partition table"). It also sees that one of the partitions in
the nested partition table, the fourth gpt partition, is improperly
nested. My guess would be that "improper" here means that the
partition ends (or starts and ends) beyond the size of sda2. This is
partially explained by further output quoted below:

> "blkid" output:
> ________________________________________________________________
> Device           UUID                                   TYPE       LABEL
> /dev/md0p1       4d377ecd-4d50-4a46-a836-a70eba197f1e   ext2
> /dev/md0p2       d7652bab-a7eb-408d-ab76-346b89ba6642   swap
> /dev/md0p3       a5bf88f4-7fd6-44e9-b26c-df5de3557367   ext3

Since your have an array which itself is partitioned (in addition to
being made up of member partitions, these are two different things
which can be confused with each other) my guess is that since sda2 is
the first member of this array, and presumably the mdraid metadata is
not stored at the beginning of the member partitions, the GPT label
(minus the backup) is contained entirely within the beginning of sda2.
This makes it appear as though sda2 is itself partitioned, when it's
really just one member of a partitioned array. This partition table is
*not* valid for sda2, only for md0, hence grub correctly finding
something wrong.

In short, grub is seeing something that would normally be a sign of
brokenness in most cases, but in your case is probably fine. Grub is
discarding the invalid data (and should have no problem reading the
valid data) so nothing should go wrong. I believe you can safely
ignore this warning.

-- 
Jordan Uggla