Ubuntu 20.04.2 nvme0n1 partitions seem strange

Asked by tomdean on 2021-05-27

> sudo fdisk -l /dev/nvme0n1
Disk /dev/nvme0n1: 931.53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: CT1000P5SSD8
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: dos
Disk identifier: 0x2841f258

Device Boot Start End Sectors Size Id Type
/dev/nvme0n1p1 2048 1050623 1048576 512M b W95 FAT32
/dev/nvme0n1p2 * 1050624 2101247 1050624 513M ef EFI (FAT-12/16/32)
/dev/nvme0n1p3 2103294 1953523711 1951420418 930.5G 5 Extended
/dev/nvme0n1p5 2103296 1953523711 1951420416 930.5G 83 Linux

But, lsblk thinks p3 is 1K ???
> lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 931.5G 0 disk
`-sda1 8:1 0 931.5G 0 part /dump
nvme0n1 259:0 0 931.5G 0 disk
|-nvme0n1p1 259:1 0 512M 0 part
|-nvme0n1p2 259:2 0 513M 0 part /boot/efi
|-nvme0n1p3 259:3 0 1K 0 part
`-nvme0n1p5 259:4 0 930.5G 0 part /

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Manfred Hampl (m-hampl) said :
#1

This seems to be common, see e.g. https://unix.stackexchange.com/questions/128290/what-is-this-1k-logical-partition

An extended partition uses the first few bytes (at least 512) for storing the information about logical partitions inside the extended partition. Apparently lsblk displays only the size of that extended boot record and not the total size of the extended partition.
In your case the extended partition starts at block 2103294 and the first (and only) logical partition in it starts at block 2103296
The difference of 2 blocks with 512 bytes each is 1k.

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