Subject: Re: GRUB dual-boot with Ubuntu 22 won't remember Windows 7 as last
used, chooses Windows 10 instead
On 16/04/2024 19:21, Paul wrote:
On 4/16/2024 9:46 AM, Java Jive wrote:
On 16/04/2024 14:05, Carlos E.R. wrote:
On 2024-04-16 14:32, Java Jive wrote:
As indicated in another post, I have solved the problem, which was caused by the two partitions having identical GUIDs, the W10 being an in-place upgrade of the W7 one. Changing the partition GUID of the W10 partition resolved the problem.
I should have noticed it:
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 C00A7FAA0A7F9BDA
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 C00A7FAA0A7F9BDA
Arguably, so should I! However, at the time of my OP I didn't know enough about GRUB to realise those numbers were the GUIDs of the partitions. It was J.O.Aho's remark, on first reading apparently insignificant, that later came back to me, causing me to investigate further and so realise that they were the GUIDs of the partitions involved.
And is that really a GUID ?
I've seen several lengths of disk identifier Linux uses
from Windows stuff, and it's not clear how it
parses or understands things like that. Or for that
matter, what generic term we should use for the identifier.
To me, it seems Linux does not get 128 bit numbers from Legacy Windows
for identifiers, the numbers tend to be 64 bit or 32 bit (DiskID).
At least I can understand the DiskID one, because I've seen it
in a hex editor.
As far as I can tell, nomenclature varies, not just between OSs, but
also between different utilities supplied with or third party programs
running on a single OS, and between different people discussing the same
thing in the same online forum ...
In grub.cfg, we have seen that the hex strings under discussion are effectively some sort of partition or volume ID. In many sources
online, they are referred to as partition IDs, however ...
In GPartEd, rt-clicking a partition and choosing Information describes
it as a UUID, so that is what I will call it/them henceforth. Once that
is understood, it then becomes apparent that rt-clicking a partition
gives a further choice of New UUID which can be chosen to change it far
more easily than the rigmarole that I went through.
However, in DiskPart, listing the details of neither a partition nor a
volume shows anywhere by any name the UUIDs shown in Linux utilities ...
DISKPART> select disk 0
Disk 0 is now the selected disk.
DISKPART> list part
Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 Primary 64 GB 1024 KB
Partition 2 Primary 64 GB 64 GB
Partition 3 Primary 32 GB 128 GB
Partition 0 Extended 287 GB 160 GB
Partition 4 Logical 143 GB 160 GB
Partition 5 Logical 143 GB 303 GB
DISKPART> select part 1
Partition 1 is now the selected partition.
DISKPART> detail part
Partition 1
Type : 07
Hidden: No
Active: Yes
Offset in Bytes: 1048576
Volume ### Ltr Label Fs Type Size Status
Info
---------- --- ----------- ----- ---------- -------
--------- --------
* Volume 1 C Win10Pro NTFS Partition 64 GB Healthy
DISKPART> select volume 1
Volume 1 is the selected volume.
DISKPART> detail volume
Disk ### Status Size Free Dyn Gpt
-------- ------------- ------- ------- --- ---
* Disk 0 Online 447 GB 1024 KB
Read-only : No
Hidden : No
No Default Drive Letter: No
Shadow Copy : No
Offline : No
BitLocker Encrypted : No
Installable : Yes
Volume Capacity : 63 GB
Volume Free Space : 9 GB
.... while, just to cause further confusion, DiskPart's SETID command
change the partition *TYPE* ID, not any sort of volume or partition UUID
or label.
In DiskGenius, the UUID is called a 'Volume ID'.
No wonder so many of us are confused in life ...
With GPT, both the partition type and the partition identifier,
they could be 128 bit numbers (disktype can show you those, maybe
gparted as well). Then the formatting would look like a GUID.
Partition 3: 118.7 GiB (127481675776 bytes, 248987648 sectors from 239616)
Type Basic Data (GUID A2A0D0EB-E5B9-3344-87C0-68B6B72699C7) <=== fixed declaration
Partition Name "Basic data partition"
Partition GUID 6A16D60B-3608-4140-891C-792DF2C72ABD <=== random assignment of some sort
NTFS file system
Volume size 118.7 GiB (127481675264 bytes, 248987647 sectors)
Yes, but not strictly relevant to my original problem.
--
Fake news kills!
I may be contacted via the contact address given on my website: www.macfh.co.uk
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