Talk:Partitioning

Partition Alignment Verification

[moved from Talk:Solid State Drives#Partition Alignment Verification -- Lahwaacz (talk) 20:13, 10 July 2014 (UTC)]

On my system 'blockdev --getalignoff /dev/sda5' returns zero, even though the partition seems not to be aligned optimally:

Disk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors
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: 0xd9a92553

Device    Boot     Start       End    Blocks  Id System
/dev/sda1 *         2048   1026047    512000   7 HPFS/NTFS/exFAT
/dev/sda2        1026048 479475711 239224832   7 HPFS/NTFS/exFAT
/dev/sda3      946051072 976771071  15360000   7 HPFS/NTFS/exFAT
/dev/sda4      479475712 946051071 233287680   5 Extended
/dev/sda5      479475775 518545791  19535008+ 83 Linux
/dev/sda6      518545855 541984626  11719386  83 Linux
/dev/sda7      541984690 557615871   7815591  82 Linux swap / Solaris
/dev/sda8      557615935 946051071 194217568+ 83 Linux

The command 'parted /dev/sda align-check optimal' gives the right message in my opinion: 'not aligned'. Should we replace blockdev command?

Plk (talk) 18:31, 31 May 2014 (UTC)

It seems you're right. After reading the warning about cfdisk alignment ("Warning: The first partition created by cfdisk starts at sector 63, instead of the usual 2048. This can lead to reduced performance on SSD and advanced format (4k sector) drives. It will cause problems with GRUB2, but GRUB legacy and Syslinux should work fine."), I created the first partition of the SSD I was working on with cfdisk - thus creating a bad alignment (I checked with fdisk -l /dev/sda, the first partition effectively starts at sector 63 and not 2048).

The blockdev --getalignoff /dev/sda1 command returned zero (it shouldn't have) while your command parted /dev/sda align-check optimal returned 'not aligned', as expected.

It seems to be a bug of blockdev in ArchLinux, as of util-linux v.2.24.

I upgraded to util-linux v.2.25-3, and the problem is still present in blockdev. However, cfdisk has been entirely rewritten for util-linux 2.25 as described in this blog post and now correctly starts the first partition at sector 2048 when creating it.

So should we edit the wiki page for recommanding upgrade to util-linux 2.25 in order to use cfdisk with correct partition alignment ? As util-linux integrates multiple essential softwares, I don't know if upgrading it will or not break something with the other utilities it includes.

In any case, I think we should disrecommend using blockdev to check partition alignment, and recommend using parted instead for the time being. Can anyone else confirm this bug, especially on other distributions ? We need to know if the problem is inherent to Arch's implementation of blockdev or to blockdev itself.

--Irrodeus (talk) 01:56, 6 September 2014 (UTC)

Restructuring

Example tables

[1] moved tables from the Beginners' guide to Partitioning#Partition_scheme, however it didn't fit in too well so I've removed it for now.

However, I think the basic idea is a sound one, but perhaps more expansive. We could include suggested File systems, as well as more complex examples such as /var and GRUB Boot partitions.

See the updated tables from the BG below for reference. -- Alad (talk) 00:20, 10 July 2016 (UTC)

Table draft

UEFI/GPT example layout
Mount point	Partition	Partition type (GUID)	Bootable flag	Suggested size
/boot	/dev/sdx1	EFI System Partition	Yes	260–512 MiB
[SWAP]	/dev/sdx2	Linux swap	No	More than 512 MiB
/	/dev/sdx3	Linux	No	Remainder of the device
MBR/BIOS example layout
Mount point	Partition	Partition type	Bootable flag	Suggested size
[SWAP]	/dev/sdx1	Linux swap	No	More than 512 MiB
/	/dev/sdx2	Linux	Yes	Remainder of the device

I added these tables to the page. I also added one using a separate /home since I imagine that is the most common scenario. I think 3 examples could be enough, but I am open to more. -- Rdeckard (talk) 18:53, 11 October 2016 (UTC)

Nice work. One thing I was considering is to have multiple small tables under the various partition sections (like /home), instead of a single large one. Thoughts? -- Alad (talk) 18:56, 13 October 2016 (UTC)

edit: I noticed you already split the tables; that leaves whether it makes sense to have them under sections like Partitioning#.2Fhome rather than Partitioning#Example layouts. -- Alad (talk) 19:01, 13 October 2016 (UTC)

All examples include the / partition and swap. Avoiding duplication and forward references is probably one of the reasons why people invented appendix. -- Lahwaacz (talk) 19:15, 13 October 2016 (UTC)

Table draft 2

BIOS/MBR

Mount point on the installed system	Partition	Partition type ID	Boot flag	Suggested size
[SWAP]	/dev/sda1	82: Linux swap	No	More than 512 MiB or the size of RAM to use hibernation
/	/dev/sda2	83: Linux	Yes	Remainder of the device
N/A	None	Unallocated space	N/A	At least 16.5 KiB

BIOS/GPT with GRUB

Mount point on the installed system	Partition	Partition type GUID	Partition attributes	Suggested size
None	/dev/sda1	21686148-6449-6E6F-744E-656564454649: BIOS boot partition		1 MiB
[SWAP]	/dev/sda2	0657FD6D-A4AB-43C4-84E5-0933C84B4F4F: Linux swap		More than 512 MiB or the size of RAM to use hibernation
/	/dev/sda3	4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709: Linux x86-64 root (/)		Remainder of the device

BIOS/GPT with Syslinux

Mount point on the installed system	Partition	Partition type GUID	Partition attributes	Suggested size
[SWAP]	/dev/sda1	0657FD6D-A4AB-43C4-84E5-0933C84B4F4F: Linux swap		More than 512 MiB or the size of RAM to use hibernation
/	/dev/sda2	4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709: Linux x86-64 root (/)	2: Legacy BIOS bootable	Remainder of the device

UEFI/GPT with a boot loader which has a driver for your root file system (eg. GRUB, rEFInd)

Mount point on the installed system	Partition	Partition type GUID	Partition attributes	Suggested size
/efi	/dev/sda1	C12A7328-F81F-11D2-BA4B-00A0C93EC93B: EFI system partition		260 MiB
[SWAP]	/dev/sda2	0657FD6D-A4AB-43C4-84E5-0933C84B4F4F: Linux swap		More than 512 MiB or the size of RAM to use hibernation
/	/dev/sda3	4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709: Linux x86-64 root (/)		Remainder of the device

UEFI/GPT with a boot loader without file system drivers or without a boot loader at all

Mount point on the installed system	Partition	Partition type GUID	Partition attributes	Suggested size
/boot	/dev/sda1	C12A7328-F81F-11D2-BA4B-00A0C93EC93B: EFI system partition		260 MiB
[SWAP]	/dev/sda2	0657FD6D-A4AB-43C4-84E5-0933C84B4F4F: Linux swap		More than 512 MiB or the size of RAM to use hibernation
/	/dev/sda3	4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709: Linux x86-64 root (/)		Remainder of the device

BIOS&UEFI/GPT with GRUB

Mount point on the installed system	Partition	Partition type GUID	Partition attributes	Suggested size
None	/dev/sda1	21686148-6449-6E6F-744E-656564454649: BIOS boot partition		1 MiB
/efi	/dev/sda2	C12A7328-F81F-11D2-BA4B-00A0C93EC93B: EFI system partition		260 MiB
[SWAP]	/dev/sda3	0657FD6D-A4AB-43C4-84E5-0933C84B4F4F: Linux swap		More than 512 MiB or the size of RAM to use hibernation
/	/dev/sda4	4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709: Linux x86-64 root (/)		Remainder of the device

BIOS&UEFI/GPT with Syslinux

Mount point on the installed system	Partition	Partition type GUID	Partition attributes	Suggested size
/boot	/dev/sda1	C12A7328-F81F-11D2-BA4B-00A0C93EC93B: EFI system partition	2: Legacy BIOS bootable	260 MiB
[SWAP]	/dev/sda2	0657FD6D-A4AB-43C4-84E5-0933C84B4F4F: Linux swap		More than 512 MiB or the size of RAM to use hibernation
/	/dev/sda3	4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709: Linux x86-64 root (/)		Remainder of the device

I didn't like the current Partitioning#Example layouts so I tried to make better ones, but I think I made too many of them. I'm not entirely certain if "GPT + BIOS & UEFI with Syslinux" is a good idea due to all of Syslinux's limitations, but GRUB doesn't use the "Legacy BIOS bootable" attribute and without the Syslinux example the whole column would become useless. Thoughts? -- nl6720 (talk) 10:19, 1 January 2018 (UTC)

If syslinux needs special mention in a manner that is exclusive to it, then I'd argue that the column is useless anyway except to draw attention to syslinux. It seems like a Note would be better for that, assuming we want to recommend syslinux at all. -- Eschwartz (talk) 05:30, 9 December 2018 (UTC)

It's not really Syslinux specific, theoretically the "Legacy BIOS bootable" attribute should be needed by any boot loader that puts stuff in the VBR (I wonder if that's also true for GRUB in VBR). -- nl6720 (talk) 09:06, 9 December 2018 (UTC)

I think that's out of scope, if the user uses some bootloader which turns out to require a bootable flag, it's simple to go back into the ISO and set the flag accordingly. This is different from say, a BIOS Boot Partition (for GRUB) which would require actual changes in partitioning if not considered beforehand.

As such I suggest to go with the following:

BIOS (MBR and GPT)

• BIOS Boot Partition
• /
• swap (as Btrfs does not support swap files, and the examples should be as generic as possible)

UEFI

• EFI System Partition
• /
• swap

-- Alad (talk) 20:35, 20 December 2018 (UTC)

The same reasoning applies to the "Boot flag" column in the BIOS/MBR example, so if we remove "Partition attributes" then we should also remove "Boot flag". -- nl6720 (talk) 06:51, 21 December 2018 (UTC)

mmcblk0p{1,2,3,4}, mmcblk0boot{0,1}, mmcblk0rpmb

And my install usb showed up as sda instead.. Don't know how to best deal with that. "Boot" ones don't seem to provide disklabel type and identifier information, and are only 4MiB. My guess is to ignore them. /dev/mmcblk0p3 seems to be the one with windows on it.(ASUS Vivobook E200HA)Jasper1984 (talk) 00:58, 25 December 2016 (UTC)

Ended up just ignoring the mmcblk0boot{0,1} entries, treating mmcblk0p{1,2,3,4} as if were just sda, basically, it worked. (dont see the rpmb volumes now) More specifically, didnt reformat the first partition, instead just putting different files there. Tried the bind-mount approach in EFI System Partition, but ended up the more regular approach. (not sure why it didnt co-operate) Would suspect that mmcblk0boot{0,1} dont matter much, but would suggest just reusing the first partition nevertheless..(really, little reason to reformat that?)Jasper1984 (talk) 00:34, 14 January 2017 (UTC)

Wikipedia definition

I noticed that Device_file and File_systems both use Wikipedia to define their articles, but Partitioning did not. I took a look at the Wikipedia article for it, and it does seem suitable enough for this article, so I went ahead and wrote that in. I'm not sure what the consensus is on using Wikipedia as an "upstream" reference, but in this case, it fits well, I think.

My only concern is that the summary now neglects to differentiate block devices from hard disks, which a reader will only discover later in the article.

Wheatgold (talk) 15:54, 8 September 2020 (UTC)

Verity and Verity Sign partition types and DPS

It seems this page should have some discussion of the verity partition types, and recommended partition layouts that include these partitions.

I'm still learning about these, and if/how they should be deployed, and came to the archwiki Patitioning page for information.

The many types of partitions available for GPT partition schemes are described here:

https://uapi-group.org/specifications/specs/discoverable_partitions_specification/

Some description of these features is given within this post:

https://0pointer.net/blog/fitting-everything-together.html

However it's a general description, and there is not concrete advice on how to deploy.

With archlinux's deep embrace of all things systemd, it seems this type of partition layout would be included.

—This unsigned comment is by Android (talk) 18:43, 28 December 2022‎. Please sign your posts with ~~~~!

dm-verity has its own page. Not everything has to be described on a single page. — Lahwaacz (talk) 18:56, 28 December 2022 (UTC)