|Summary:||Autodetection of md devices works not after superblock 1.0 was introduced|
|Product:||IO/Storage||Reporter:||Lennart Andre Rolland (lennart)|
Description Lennart Andre Rolland 2006-09-26 11:53:17 UTC
Most recent kernel where this bug did not occur: none Distribution: Gentoo 2006.1 Hardware Environment: SiL 3112 SATA controller Seagate 80GiB SATA x 2 Software Environment: Very basic install, no software installed except the bare gentoo system. Grub as boot loader kernel is built with no modules and module support turned off kernel is built with support for raid0, raid1, md, autmounter4, scsi, SiL3112, XFS Problem Description: I have two sata drives and i want my root to be a software raid-0 (striped). I created a partition layout like so: /dev/sda1: 100MiB TYPE 83 (linux) /dev/sda2: 8GiB TYPE 82 (swap) /dev/sda2: 70GiB TYPE FD (linux MD autodetect) /dev/sdb1: 100MiB TYPE 83 (linux) /dev/sdb2: 8GiB TYPE 82 (swap) /dev/sdb2: 70GiB TYPE FD (linux MD autodetect) I prepared a boot partition by making a file system on /dev/sda1 I prepared my root partition as an md device like so: mdadm -A -a yes /dev/md0 -l 0 -n 2 /dev/sda3 /dev/sdb3 #(ASSEMBLE, create missing device file automatically, raid level 0, number of devices = 2, device list) I verified that it worked with cat /proc/mdstat and build a filesystem on top of it. I preceeded with mounting it and installing gentoo like usual. my grub.conf says: kernel /vmlinuz root=/dev/md0 Everything went smooth untill reboot. I get: md: Autodetecting md devices md: Autodetection complete (indicating that no md devices were found) A few lines later i get: md: unknown device "md0" or unknown block device (9,0) VFS: Kernel panic (something about root= parameter not set right). I have done the EXCACT same install procedure successfully several times before so this puzzled me. After immense digging and troubleshooting (and many reinstallations) I found a hint on the internet, that this might be caused by the latest mdadm switching from v0.7 to v1.0 superblock ,and that the latest kernel might not discover them at boot. I found that this is handled in the /usr /src/linux*/init/do_mounts_md.c. Hopefully this will be fixed so that I may 1. avoid using initrd and 2. avoid reinstalling with 0.7 superblocks. Thanks!! Steps to reproduce: Allready explained.
Comment 1 Lennart Andre Rolland 2006-09-28 07:01:44 UTC
I discovered a few typos. First i didnt use the assemble command with mdadm to create the array, i used - C for create. Second the error message just before kernel panic is a "from my memory". Nontheless all the important datas are there.
Comment 2 Sven Strickroth 2007-01-21 07:20:33 UTC
i've the same problem, after updating kernel 2.6.14.x to 18.104.22.168... with 22.214.171.124 no raid-problems (but security related ones).
Comment 3 Neil Brown 2007-01-21 18:38:55 UTC
1- in-kernel autodetect does not work with version-1 metadata. This is by design. You should be using 'mdadm -As' or similar in an initrd if you are using version-1 metadata. 2- mdadm does not default to version-1 metadata unless it is told to. It can be told to by a 'CREATE' line in mdadm.conf. If you are using Debian, you probably have that CREATE line, but you should also get a kernel with an initrd that does the right thing. 3- Upgrading the kernel should have no effect here. If it really does, more details are needed. I suggest you "get with the program" and use an initrd. There are instruction in the mdadm release for building an ultra-simple initrd just for md. Or you can read the "mkinitramfs" (or whatever) doco for your distribution and do it that way. It really isn't very hard.
Comment 4 Sven Strickroth 2007-01-24 06:48:12 UTC
"mdadm --examine /dev/hdb1 /dev/hdb1: Magic : a92b4efc Version : 00.90.00 UUID : 39006600:1cbd44af:086b834c:a4495afa Creation Time : Sun Jun 25 13:53:28 2006 Raid Level : raid1 Device Size : 32000 (31.26 MiB 32.77 MB) Array Size : 32000 (31.26 MiB 32.77 MB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 0 Update Time : Wed Jan 24 05:30:39 2007 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Checksum : 35f3b3d5 - correct Events : 0.466 Number Major Minor RaidDevice State this 0 3 65 0 active sync /dev/hdb1 0 0 3 65 0 active sync /dev/hdb1 1 1 22 1 1 active sync /dev/hdc1" If I read this info correctly I have a 0.9 metadata!?
Comment 5 Sven Strickroth 2007-03-27 15:31:12 UTC
My problem reported above doesn't exist any more, with vanilla kernel 126.96.36.199 it works again.
Comment 6 Adrian Bunk 2007-03-27 16:14:07 UTC
Thanks for this information.