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#1 2019-04-20 02:22:45

JimDeadlock
Member
From: London
Registered: 2019-03-20
Posts: 71

[SOLVED] NVMe and RAID

I wasn't sure where to post this, but since I'm new to Arch and never attempted RAID before I thought I'd put it here...

I have a pair of 'Samsung SSD 970 EVO Plus 1TB' M.2 PCIe sticks, I want to put them in a RAID 0 volume (yes, I'm aware of the risks) and then install Arch on the volume.

I've created the RAID 0 volume in BIOS and it looks fine. I switched from AHCI to the RAID mode (it's a long-winded name) and booted an Arch live session. When I try 'lsblk' or 'fdisk -l' it only shows my other partitions but not the RAID volume. If I switch back to AHCI then Arch can see the individual drives, but that's no good to me. I also tried Ubuntu but that can't see the volume either.

Does anyone know if this is even feasible?

Last edited by JimDeadlock (2019-04-20 12:17:24)

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#2 2019-04-20 09:06:39

nl6720
The Evil Wiki Admin
Registered: 2016-07-02
Posts: 592

Re: [SOLVED] NVMe and RAID

What you are trying to use is firmware based RAID (a.k.a fake RAID). Try reading https://wiki.archlinux.org/index.php/In … _Fake_RAID. The page looks a little dated, but maybe you can find something useful there.
If Linux doesn't have a driver for your RAID, then you can always use software RAID.

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#3 2019-04-20 11:57:23

JimDeadlock
Member
From: London
Registered: 2019-03-20
Posts: 71

Re: [SOLVED] NVMe and RAID

Thanks for the pointers, the Fake RAID article is exactly what I've been looking for, I'm off to read it now.

In an ideal world I would prefer to use mdadm, but the problem is that Arch has to be installed before you can use mdadm, which is why I need to use a BIOS-based RAID in order to have it set on an empty, fresh volume ready to install Arch on it, if you see what I mean.

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#4 2019-04-20 12:13:00

loqs
Member
Registered: 2014-03-06
Posts: 17,196

Re: [SOLVED] NVMe and RAID

RAID#Installing_Arch_Linux_on_RAID covers where in following the installation guide you should perform mdadm specific steps.
These can be accomplished from the installation media.

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#5 2019-04-20 12:17:01

JimDeadlock
Member
From: London
Registered: 2019-03-20
Posts: 71

Re: [SOLVED] NVMe and RAID

Even better, thanks!

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#6 2019-04-20 12:21:50

loqs
Member
Registered: 2014-03-06
Posts: 17,196

Re: [SOLVED] NVMe and RAID

Just to note depending on the boot loader you use you will need a filesystem which is not on RAID i.e. you would create each device with two partitions one for RAID and a small none RAID one.

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#7 2019-04-20 12:30:46

JimDeadlock
Member
From: London
Registered: 2019-03-20
Posts: 71

Re: [SOLVED] NVMe and RAID

OK so you're saying for example I would install GRUB on /dev/sda (non-RAID) which would then boot Arch on my RAID volume, right?

So this leads me to explain the purpose of wanting RAID 0 in the first place - my main priority is speed. These M.2 sticks are blisteringly fast and I want to make them even faster, especially during the boot process smile Using a BIOS-based RAID will allow me to boot straight into Arch without having to go through a boot loader - I know it's only a couple of seconds, but it all counts! Anyway I do appreciate all the info, I'm going to read it all before deciding on the best method. I was coming up empty on Google, I guess this is why I'm an Arch noob, shoulda checked the wiki first.

EDIT: so I started reading about Fake RAID and the first thing it starts talking about is a bootloader... is it not not possible to install Arch with EFI and then boot it directly via the BIOS in UEFI mode without a separate bootloader?

Last edited by JimDeadlock (2019-04-20 12:40:28)

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#8 2019-04-20 12:40:28

loqs
Member
Registered: 2014-03-06
Posts: 17,196

Re: [SOLVED] NVMe and RAID

You would partition sda to sda1,  sda2 and sdb to sdb1, sdb2 ensuring the sizes of each partition match.
Then yes put grub on sda1 and sdb1 remains unused but keeps the devices aligned.
The RAID would be made up of sda2 and sdb2.

Last edited by loqs (2019-04-20 12:40:45)

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#9 2019-04-20 12:40:33

frostschutz
Member
Registered: 2013-11-15
Posts: 1,409

Re: [SOLVED] NVMe and RAID

avoid fake raid like the plague

if there will only be linux on this system, go with mdadm

Arch has to be installed before you can use mdadm

you can set it up from live cd same way you set up regular partitions and filesystems

make sure to remove traces of bios raid first (bios to ahci, wipe start and end of drive)

Last edited by frostschutz (2019-04-20 12:41:06)

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#10 2019-04-20 12:45:26

JimDeadlock
Member
From: London
Registered: 2019-03-20
Posts: 71

Re: [SOLVED] NVMe and RAID

That seems so weird, GRUB is usually on the bare metal and invisible... so once Arch is installed I would be booting in legacy mode, there's no EFI partition or UEFI shenanigans?

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#11 2019-04-20 12:48:29

frostschutz
Member
Registered: 2013-11-15
Posts: 1,409

Re: [SOLVED] NVMe and RAID

you can do legacy or uefi as per your preference

it's common to have the bootloader / boot partition as a simple mirror on either drive, and then the raid level for data partition.

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#12 2019-04-20 12:54:20

Slithery
Administrator
From: Norfolk, UK
Registered: 2013-12-01
Posts: 5,776

Re: [SOLVED] NVMe and RAID

JimDeadlock wrote:

...GRUB is usually on the bare metal and invisible...

I'm not sure quite what you mean by that? GRUB is always installed on one of your drives.

It lives in either the free space before the partition table (BIOS firmware + msdos partitioning), the specialised GRUB BIOS partition (BIOS firmware + GPT partitioning), or the EFI partition (UEFI firmware). In no sense is it stored on the 'bare metal'.


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

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#13 2019-04-20 13:00:29

JimDeadlock
Member
From: London
Registered: 2019-03-20
Posts: 71

Re: [SOLVED] NVMe and RAID

Slithery wrote:

In no sense is it stored on the 'bare metal'.

Well yes, I just meant on sda rather than sda1 (so I don't see it as a partition in Gparted for example). I'm not very good with the lingo sorry sad

frostschutz wrote:

you can do legacy or uefi as per your preference

it's common to have the bootloader / boot partition as a simple mirror on either drive, and then the raid level for data partition.

What do you mean by 'simple mirror'? My tiny brain is about to explode with all this... What loqs said was to have sda1+sdb1 (for GRUB) and sda2+sdb2 (for /, /home, etc) and this would all be within the RAID. I can get my head around that, but you're saying that usually people only use the RAID for their /home ?

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