[gentoo-user] hardware disk description

[gentoo-user] hardware disk description

[Jude DaShiell]

My machine has protected mbr with gpt partitions on it.  Are those kind of
partitions hybrid?


--
 Jude <jdashiel at panix dot com>
 "There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo.
 Please use in that order."
 Ed Howdershelt 1940.

Re: [gentoo-user] hardware disk description

[karl]

Jude DaShiell:
> My machine has protected mbr with gpt partitions on it.  Are those kind of
> partitions hybrid?

 Why not check for yourself:
https://en.wikipedia.org/wiki/GUID_Partition_Table

 You can use theese to find out what you have:
file -s /dev/sda
fdisk -l /dev/sda

Regards,
/Karl Hammar

Re: [gentoo-user] hardware disk description

[Wols Lists]

On 28/05/2024 20:51, Jude DaShiell wrote:
> My machine has protected mbr with gpt partitions on it.  Are those kind of
> partitions hybrid?
> 

This is completely standard nowadays. I think the "protected MBR" just 
points to the first four GPT partitions.

This is basically down to the fact that (a) the MBR can no longer 
describe a modern large disk (I'm not sure what the limit is, 2TB? 
4TB?), and also older formatting tools - if they don't see an MBR - are 
known for assuming the disk is empty and trashing the start of it. Yeah 
they shouldn't, but they do ...

Cheers,
Wol

Re: [gentoo-user] hardware disk description

[Michael]

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On Wednesday, 29 May 2024 00:10:07 BST Wols Lists wrote:
> On 28/05/2024 20:51, Jude DaShiell wrote:
> > My machine has protected mbr with gpt partitions on it.  Are those kind of
> > partitions hybrid?
> 
> This is completely standard nowadays. I think the "protected MBR" just
> points to the first four GPT partitions.
> 
> This is basically down to the fact that (a) the MBR can no longer
> describe a modern large disk (I'm not sure what the limit is, 2TB?
> 4TB?), and also older formatting tools - if they don't see an MBR - are
> known for assuming the disk is empty and trashing the start of it. Yeah
> they shouldn't, but they do ...
> 
> Cheers,
> Wol

The 'protective MBR' is a partition type 0xEE starting at sector 0 and 
spanning the entire length of a disk (or 2TiB).  Legacy partitioning tools 
which do not recognise GUID Partition Table structures will identify a GPT 
disk to have no free space left, instead of mistakenly consider it 
unpartitioned.

A hybrid MBR is a variant of the protective MBR and it also contains up to 3 
additional primary partitions occupying the same space as up to 3 GPT 
partitions.  Older OSs which cannot boot from GPT disks should be installed 
there, while modern OSs will be able to use the remaining GPT partitions on 
the disk.

Unless gdisk declares "MBR partitions" with their Status as "primary", you do 
not have a hybrid MBR or any primary partitions on your disk.

You can check this page for more information:

https://wiki.gentoo.org/wiki/Hybrid_partition_table

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