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I would like to use systemd on my Gentoo box. Unfortunately, I have /usr on a separate partition and Gentoo puts libdbus into /usr/lib, leading to a segfault on boot, since systemd relies on dbus.

Hence I would like to generate an initramfs using dracut that mounts /usr for me. This partition is on an md raid. I think that I have setup dracut correctly to include mdadm, but somehow it does not mount /usr

I think that it is configured to only mount the root partition by default, even if it detects other partitions.

How can I tell dracut to mount /usr also before switching to the real init?

share|improve this question
Just curios, Is there a good reason to put /usr on a separate partition? – user606723 Aug 4 '11 at 20:32
Not in my case, no. It's just that it is a bit complicated to change this in the current setup, and I thought that creating an initramfs using dracut would be a simple task that solved the problem until I manage to repartition the machine. – lytenyn Aug 5 '11 at 6:29

I may have found a solution by digging through a lot of forums. For a cross-distribution framework, documentation certainly is scarce.

There is a dracut-module called fstab-sys, which reads /etc/fstab.sys and mounts all partitions mentioned there. The format is the same as the one of /etc/fstab.

To sum up, I had to create /etc/fstab.sys containing /usr/ and create the dracut image with something like

dracut -a fstab-sys --mdadmconf -H "" <kernel_version>

Warning: I could not test this yet. I will remove this warning once this is verified.

share|improve this answer
Unfortunately, I could not verify this yet, since I seem to have problems with the mdraid module also.. – lytenyn Aug 15 '11 at 7:27
It does not work. But it might be a dracut bug, since I am fairly sure this is how it is supposed to be... – lytenyn Sep 8 '11 at 15:50

From dracut-012 NEWS:

 8 - try to mount /usr, if init points to a path in /usr
share|improve this answer
Thank you, that is indeed interesting but will not help, since systemd is at /bin/systemd, it just uses libdbus which is in /usr/lib. – lytenyn Aug 15 '11 at 7:26

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