I believe Gentoo suffers from the same problem as Red Hat does (see https://bugzilla.redhat.com/show_bug.cgi?id=543749) - namely if one is using md device composed of partitions which extend to the end of the device, blkid included in genkernel generated initramfs will incorrectly assume the whole device is part of mdraid and will not look for partitions on it. I presume this is not specific to genkernel's initramfs only. Regardless of the fact that a gap of at least 128MiB is recommended after each GPT (and probably also MBR) partition (with the exception of EFI System Partition and BIOS Boot Partition), blkid shouldn't make erroneous assumptions about md superblocks at the end of the devices. Superblock formats 0.90 and 1.0 are both located at the end of devices/partitions and while format 1.0 holds additional offset information, format 0.90 as momentarily the only one supported by GRUB2, does not. Reproducible: Always Steps to Reproduce: 1. Create two partitions on every device that will be included in mdraid - 2nd partition should should extend fully to the end of the device 2. Create any type of mdraid from 2nd partitions 3. Reboot 4. Mdraid won't assemble, partiotions on constituting device won't show anymore
This was fixed in util-linux-2.18 in commit c81e70087cfebc299bdfbbd0675958483fc8a768 https://www.kernel.org/pub/linux/utils/util-linux/v2.18/v2.18-rc1-ChangeLog
https://git.kernel.org/?p=utils/util-linux/util-linux.git;a=commit;h=c81e70087cfebc299bdfbbd0675958483fc8a768
(In reply to comment #1) thanks for the heads up !
