Arch Linux

jackro

Member

Registered: 2014-09-21

Posts: 14

Kernel won't detect software RAID0 on boot, Arch USB finds it

Hello. I've got an Acer Aspire S7 that comes with two 128G SSD's setup in RAID0 by default. When installing Arch on it, I see the USB automatically finds this RAID setup and creates /dev/md126. So I went ahead and removed the Windows partitions from /dev/md126 and made my own Arch partitions, gummiboot at /dev/md126p1, swap at /dev/md126p2, and the root partition, ext4, at /dev/md126p3.

I went ahead and followed the instructions on the Arch Wiki for a RAID setup by adding mdadm_udev (I've tried just mdadm too) to the hooks in my /etc/mkinitcpio.conf. Then I added the output of mdadm --detail --scan to my /mnt/etc/mdadm.conf (outside chroot). That results in something that looks like:

DEVICE partitions
ARRAY /dev/md/imsm0 metadata=imsm
ARRAY /dev/md/HDD0_0 container=/dev/md/imsm0 member=0 UUID=2aa...

Then ran mkinitcpio -p linux inside the chroot. For my gummiboot, I wrote a config that looks like:

title          Arch Linux
linux          /vmlinuz-linux
initrd         /initramfs-linux.img
options        root=/dev/md126p3 rw

The computer finds the bootloader, and boots linux, however, I get stuck at searching for device /dev/md126p3 and drops me at an emergency shell. After doing some reading on mdadm, I tried updating my boot entry to read:

title          Arch Linux
linux          /vmlinuz-linux
initrd         /initramfs-linux.img
options        root=/dev/md126p3 rw md=126,/dev/sda,/dev/sdb

Still to no avail. Oddly enough, in the emergency shell, don't have /dev/md126 or any of it's related entries, but I do have /dev/sda and /dev/sdb. I also don't have any partitions listed by uuid under /dev/disk.

Any help?

Pryx

Member

From: Czech Republic

Registered: 2015-09-24

Posts: 2

Re: Kernel won't detect software RAID0 on boot, Arch USB finds it

Solving the same problem, was about to ask very similar question... I somehow managed to get it installed with GRUB about 3 months ago on my MSI GS60 laptop... Archiso works and Fedora also seems to be handling this without any problem. Not really sure what might be wrong...

//EDIT: Might be that an upstream change has broken mdadm fakeraid handling... (see this post) But that wouldn't explain why my ArchLinux install worked (fully updated), until i decided to do a complete reinstall of my Arch/Win dualboot...

Last edited by Pryx (2015-09-24 18:04:33)

rhodie

Member

Registered: 2012-03-19

Posts: 45

Re: Kernel won't detect software RAID0 on boot, Arch USB finds it

I had something similar with a RAID1 setup.  I found I needed to add raid1 to the MODULES list in mkinitcpio.conf.  I guess in your case(s?) it would be raid0.

Pryx

Member

From: Czech Republic

Registered: 2015-09-24

Posts: 2

Re: Kernel won't detect software RAID0 on boot, Arch USB finds it

I had something similar with a RAID1 setup.  I found I needed to add raid1 to the MODULES list in mkinitcpio.conf.  I guess in your case(s?) it would be raid0.

Tried in my case, no success...

chrisberkhout

Member

Registered: 2014-04-24

Posts: 5

Website

Re: Kernel won't detect software RAID0 on boot, Arch USB finds it

I'm having the same issue, but with grub. It happened after an upgrade today.
I tried downgrading the kernel and firmware. That didn't help.
I tried adding md_mod and raid0 to the MODULES section of mkinitcpio.conf, as well as adding /sbin/mdmon to BINARIES and moving mdadm_udev before encrypt in HOOKS. That didn't help either.

chrisberkhout

Member

Registered: 2014-04-24

Posts: 5

Website

Re: Kernel won't detect software RAID0 on boot, Arch USB finds it

After reading the post linked by Pryx I tried downgrading mdadm (and rerunning mkinitcpio), and that did get everything working again.
I suspect I could set IMSM_NO_PLATFORM=1 and go back to the latest mdadm, but I'm not sure how to have that variable set at the right stage of boot.

chrisberkhout

Member

Registered: 2014-04-24

Posts: 5

Website

Re: Kernel won't detect software RAID0 on boot, Arch USB finds it

I took a look inside my initramfs-linux.img for where mdadm is run, and it seems that it's done in /usr/lib/udev/rules.d/64-md-raid-assembly.rules. I haven't tried yet, but it seems that the IMSM_NO_PLATFORM variable could be set there.

EDIT: That did work. I wouldn't say it's a full solution, but it's enough for me for now. Details: https://bbs.archlinux.org/viewtopic.php … 8#p1565988

Last edited by chrisberkhout (2015-09-29 19:23:54)