I have been trying to move my root partition from a degraded raid 10 on an Intel sata controller to a new root on a marvell sata controller. The old root is /dev/md1 and the new root is /dev/md2 Both are degraded raid 10s When I try to boot with root=/dev/md2 the root is not recognized and fails with unknown block 9,2 which is /dev/md2. I can boot with no problem changing to root=/dev/md1 in grub.cfg all the drivers are built into the kernel. It seems that grub is not waiting for md2 to be assembled before accessing it. Both arrays are metadata=0.9
This is not a grub problem. unknown block 9,2 is a message from your kernel.
grub is supposed to assemble the array and does not. Then the kernel cannot find the root. I worked around the issue with an initramfs but grub does seem to have an issue with marvell sata controllers when using the built in mdraid drivers.
1) Please post your `emerge --info' output in a comment. 2) Please review the Summary and see if you agree with that wording.
grub is NOT supposed to assemble the array. Your kernel and/or initramfs does that. grub only implements read-only access for mdraid.
then why does grub have its own mdraid modules? Unfortunately I cannot test at the moment. Let me explain what I did and why I think it is a bug. I had be running with 2 1T disks in raid1 with root as sd{a,b}3 in md1 with lvm on top of md3 which were the extended partitions I was running out of root space after having to move /usr and /var off lvm because of udev and systemd so I decided to add move disks and use mdraid-10. I first moved the lvm stuff creating sdc5 missing sdd5 missing mdraid-10 that worked fine so I added in sda5 and sdb5 I wanted to be more careful with the root and make sure the new array would boot. so I made a sdc3 missing sdd3 missing mdraid-10 and copied the root to it. at this point I had sda3 sdb3 as md1 with root and sdc3 sdd3 as md2 with new root. md1 had disks on an intel sata controller and md2 disks were on a marvell sata controller At this point I could boot with root=/dev/md1 but any time I tried to boot with root=/dev/md2 I got (9,2) not found. btw 9,2 is /dev/md2. the grub.cfg was the same exactly the same except for root=. I even booted off the same boot partition which was on the marvell controller. That is why I filed the bug.
(In reply to Harris Landgarten from comment #5) > then why does grub have its own mdraid modules? > grub's mdraid code is used to load your kernel and initramfs into memory, if those happen to be stored on an mdraid volume. grub's mdraid code not used for anything once the kernel has been started. The kernel and initramfs have their own code for probing and assembling mdraid devices.
