Arch Linux

whoops

Member

Registered: 2009-03-19

Posts: 891

Soft Raid0/ext4 as /boot & grub2 (arch64)?

Hi!

I'm trying to get a raid0 installation with 2 drives running (grub2):

/boot, swap, /, /home
are
md0 (sda1, sdb1), md1 (sda2, sdb2), md2 (sda3, sdb3), md3 (sda4, sdb4)

I tried to install GRUB2 to sda&b with raid support included but after reboot I just get the grub recovery shell - ls lists sda1 to sdb4 and md0, nothing else. lsmod says the modules rais, lvs and [something that requires raid but i forgot the name and can't check atm] are loaded. "boot" says "no kernel" obviously...

I'm not sure what's going on and don't really know where to start looking for a solution - any hints?

Last edited by whoops (2009-03-30 19:29:20)

whoops

Member

Registered: 2009-03-19

Posts: 891

Re: Soft Raid0/ext4 as /boot & grub2 (arch64)?

Ok, I took another 2/3/4 closer looks at what I did there... browsing the Internet, it looks at least as if it would be possible to get that right (didn't find anything about booting from ext4 raid0, but several people seemed to get one of the two working without much problems - still got no idea how to find out what I did wrong.

- How can I tell, if my grub2 has problems with ext4 as boot partition?
- How do I find out, if my grub2 doesn't manage to get boot from raid0 right?
- Could this just be a "ext4/raid0 - interaction" - Problem? How know?
- What's the best starting point to figure out what I'm doing wrong?

Thanks for any hint - so if someone can just tell: "it's possible, I did it" without any further explanations, that would already be something on my list not to just forget about it and replace md0/ext4 with a standard sda/ext3.

edit:
3 times switching cables & 6 boots later...:

The installation still seems intact - at least I'm able to assemble & mount the raids and use pacman when chroot'ed inside - no files disappearing or something like that, everything seems to be where it should be, the files in /boot disappear as they should when I mkfs md0...

- grub-probe says something like"filesystem not recognized"
- grub2 says the same thing when trying to ls (md0) or boot from md0
- I mkfs'd md0 to ext3 and got the same error.
- Then I mkfs'd md0 to ext2 and got the same error again.

I tried grub-install --modules="ext2 raid" /dev/md0 which did something: the grub "emergency shell" now says ext2 is integrated when I type lsmod. This should mean - i guess - that grub's sort of starting from md0 bootsector, because:

When I tried grub-install with ext2 & raid on sda / sdb, it told me that the image was to big (one of them alone did work), so the grub on sda/b shouldn't have had ext2.

I found a list of modules I maybe should add to grub-install somewhere (modules="linux raid ........"), but it tells me there's not enough space to include even the linux-module alone.

I have not been able to find a grub2 manual of any kind anywhere - the ones i get with "man grub-install" etc. are all empty and google seems to enjoy throwing trash at me due to my stupid idea to combine 64bit, grub2 & ext4. At least, I recently discovered a wondrous item that lets me store information outside my own memory without needing a computer (I think they're called PEN or something), so next time I try to boot the other hd's I at least will be able to collect some more accurate informations (yes, it took me incredibly long to figure that little sub-problem out).

So... help?

edit: haven't been able to figure that out, so I let sda1 & sb1 raidless for now. The rest of it (ext4, arch64, raid / & raid /home) worked fine. Guess I'm done with raid - /boot for now.

Last edited by whoops (2009-04-02 00:03:51)