01.11.2014 21:53, Stephen Kent wrote: > I have set up a machine to use an md array as the root device. I have > created the array with metadata type 1.2, name "root," on host > "optimus" (so the full metadata name is "optimus:root"). > > I'm using Gentoo Linux (kernel 3.16.5-gentoo), and previously I had no > initramfs so I wrote a short one to assemble the array. My initramfs > sets the hostname and runs "mdadm -As," which correctly auto-assembles > the root device array on /dev/md/root (even without an > /etc/mdadm.conf). > > Once the initramfs script is finished, init starts which then starts > udev. Now, at this point the array is already assembled, but the > /dev/md/* name is lost (and so is /run/mdadm/map) since those files > were on the initramfs' tempfs root. This is your problem. You should not lose neither /dev nor /run when switching root. Usual thing to do is to mount tmpfs /dev and tmpfs /run in initramfs and do mount --move /dev /root/dev (and the same for /run) before switching root. Thanks, /mjt > udev creates a /dev/mdXXX node > (ex. /dev/md127) and then runs a rule to try to figure out the > /dev/md/* name, which should be /dev/md/root. The default udev rule > calls mdadm --detail --export /dev/md127, which should print > MD_DEVNAME=root for udev, but instead it prints > MD_DEVNAME=optimus:root, and the symlink in /dev/md gets created as > /dev/md/optimus:root. > > I think this is a bug in mdadm, but I'm not sure how to dig into it. I > have made sure that my main OS init sets the hostname before starting > udev, and I have tried with and without "HOMEHOST optimus" in > /etc/mdadm.conf. > > The workaround I am using right now is to define the array name > manually in /etc/mdadm.conf like this: > > ARRAY /dev/md/root UUID=782a671c:e646f2d5:848baad0:5668ee84 > > This works by avoiding automatic name detection and using the defined > name (/dev/md/root), but it really seems that mdadm should know how to > determine MD_DEVNAME correctly for an already-started array if the > hostname (or homehost) is correctly set. Is this a bug in mdadm? If > so, is this the correct place to report it or is there a bug tracking > system I should use? I am using mdadm v3.3.1. > > (Please cc me on replies as I am not currently subscribed to the > linux-raid list.) > > Thanks, > > Stephen > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
