On Wednesday, 18 October 2023 14:57:51 BST Grant Edwards wrote: > On 2023-10-18, Michael <confabul...@kintzios.com> wrote: > >> Oh, and if you use GPT, you no longer need the MBR compatibility > >> partition, or whatever its called. I no longer need it so I can't > >> remember the exact name. > > > > Man pages of partitioning tools refer to it as "Protective MBR", although > > I've seen it mentioned in the interwebs as "protective GPT", which I > > think is more accurate. It uses the first sector (LBA 0) to store an MBR > > table showing the whole disk, or 2TB if smaller, as an MBR partition. > > This is the first partition on the disk, typically 1 MiB in size. It is > > meant to stop 20 year old partitioning tools from messing up a GPT > > partitioning scheme because they can't see it. Arguably nobody uses > > Windows 98 these days, so it should be safe to not have a protective MBR > > on your GPT disks. > > The protective MBR and the BIOS boot partition are two different, > unrelated things. The BIOS boot partition is a real partition (usually > 1-2MB in size) that's present in the GPT parition table. It's used by > Grub as a place to store its files.
Yes, this is needed on GPT disks when installed on BIOS MoBos. > It must be the first partition, > and it doesn't have a real filesystem (grub uses some sort of private > filesystem): I'm not sure it uses any filesystem. I understood it uses a raw sector jump from the MBR to the GPT partition type 0xEE. > $ sudo fdisk -l /dev/nvme0n1 > Disk /dev/nvme0n1: 465.76 GiB, 500107862016 bytes, 976773168 sectors > Disk model: Samsung SSD 980 PRO 500GB > Units: sectors of 1 * 512 = 512 bytes > Sector size (logical/physical): 512 bytes / 512 bytes > I/O size (minimum/optimal): 512 bytes / 512 bytes > Disklabel type: gpt > Disk identifier: E81DD16A-A5AE-3C4A-AD3C-26DF2985827A > > Device Start End Sectors Size Type > /dev/nvme0n1p1 2048 6143 4096 2M BIOS boot > /dev/nvme0n1p2 6144 134219775 134213632 64G Linux filesystem > /dev/nvme0n1p3 134219776 976773134 842553359 401.8G Linux filesystem This links explains the combos of BIOS vs. EFI MoBos and MBR vs. GPT partition table schemes: https://askubuntu.com/questions/500359/efi-boot-partition-and-biosgrub-partition
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