Arch Linux

dockland

Member

From: Sweden

Registered: 2015-06-06

Posts: 861

PCIe -bus becomes /dev/sdb (SOLVED)

I recently bought an SSD (Samsung 850 EVO 512 GB) to act as "storage" for my NUC, that has a PCIe (M.2 AHCI) as system disc.
I decided to reinstall Arch from scratch and whilst partitioning my PCIe was "down prioritized" by my motherboard and became /dev/sdb and my brand new SSD (SATA) is now /dev/sda

The BIOS/UEFI-settings doesn't allow any change in boot-priority or anything like that. The Intel NUC is a 5i7RYH (Broadwell)

I don't think it does matter at all, but it's kind of strange.

My question is, is there a way to make it reverse? That my PCIe becomes /dev/sda and my 850 EVO becomes /dev/sdb?

Edit: Added info M.2

Last edited by dockland (2015-10-11 10:15:27)

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I possess a device, in my pocket, that is capable of accessing the entirety of information known to man.
I use it to look at funny pictures of cats and to argue with strangers.

SaltySockets

Member

Registered: 2015-10-10

Posts: 22

Re: PCIe -bus becomes /dev/sdb (SOLVED)

The order which the drives show up is based on what the BIOS/UEFI says to the OS. So to get around this when it comes to /etc/fstab and bootloader configs is to refer to drives and partitions using UUIDs.
Once the kernel is loaded, you'll be able to decide the device names through udev rules. I've never written udev rules that set the device names of harddrives based on their serial numbers.

dockland

Member

From: Sweden

Registered: 2015-06-06

Posts: 861

Re: PCIe -bus becomes /dev/sdb (SOLVED)

The order which the drives show up is based on what the BIOS/UEFI says to the OS. So to get around this when it comes to /etc/fstab and bootloader configs is to refer to drives and partitions using UUIDs.
Once the kernel is loaded, you'll be able to decide the device names through udev rules. I've never written udev rules that set the device names of harddrives based on their serial numbers.

Thanks for your answer.

I'm going to buy a Samsung 950 Pro PCIe SSD NVMe and i'll just remove my 2.5" SSD and install Arch, then insert the SSD and mount it. Then it should be /dev/sdb

I think.

Last edited by dockland (2015-10-10 21:47:46)

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I possess a device, in my pocket, that is capable of accessing the entirety of information known to man.
I use it to look at funny pictures of cats and to argue with strangers.

Slithery

Administrator

From: Norfolk, UK

Registered: 2013-12-01

Posts: 5,776

Re: PCIe -bus becomes /dev/sdb (SOLVED)

You shouldn't rely on device names staying the same as you can never guarantee that the kernel will bring the devices up in the same order next time you boot. Use UUIDs or labels.

https://wiki.archlinux.org/index.php/Pe … ice_naming

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No, it didn't "fix" anything. It just shifted the brokeness one space to the right. - jasonwryan
Closing -- for deletion; Banning -- for muppetry. - jasonwryan

aur - dotfiles

dockland

Member

From: Sweden

Registered: 2015-06-06

Posts: 861

Re: PCIe -bus becomes /dev/sdb (SOLVED)

You shouldn't rely on device names staying the same as you can never guarantee that the kernel will bring the devices up in the same order next time you boot. Use UUIDs or labels.

https://wiki.archlinux.org/index.php/Pe … ice_naming

Yes, i'm using UUID. Actually i don't think it matter whether it's sda or sdb. Just a visual "confusion"

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I possess a device, in my pocket, that is capable of accessing the entirety of information known to man.
I use it to look at funny pictures of cats and to argue with strangers.