[gentoo-user] No /dev/sd? devices. Udev problem?

[gentoo-user] No /dev/sd? devices. Udev problem?

[Alex Schuster]

Hi there!

I just migrated a friend's machine to ~am64. Everything was updated, but 
after a reboot some partitons are not found. No wonder, there are no 
/dev/sd? devices, only /dev/sg?. I suspect the problem is udev, because 
that was updated. Root is encrypted, so this machine makes use of an 
initramfs. At that point, all devices are found, so the system comes up, 
but later mounting of data partitions fails due to the missing devices.

Any idea what the cause is? I will try to downgrade udev and see what 
happens. I have to wait for my friend to arrive here though, because I do 
not know the LUKS password. So I thought I'd ask here first, maybe someone 
knows this problem.

	Wonko

Re: [gentoo-user] No /dev/sd? devices. Udev problem?

[Alex Schuster]

I wrote:

> I just migrated a friend's machine to ~am64. Everything was updated,
> but after a reboot some partitons are not found. No wonder, there are
> no /dev/sd? devices, only /dev/sg?. I suspect the problem is udev,
> because that was updated. Root is encrypted, so this machine makes use
> of an initramfs. At that point, all devices are found, so the system
> comes up, but later mounting of data partitions fails due to the
> missing devices.
> 
> Any idea what the cause is? I will try to downgrade udev and see what
> happens. I have to wait for my friend to arrive here though, because I
> do not know the LUKS password. So I thought I'd ask here first, maybe
> someone knows this problem.

A downgrade from 151-r2 to 150-r1 did not change anything. I can try to go 
to lower versions, but I wonder what the problem is. My own machine is 
~x86 instead of ~am64, but has a similar setup, and all is working. Well, 
not all, but I spare you my KDE4 rants for the moment.

The missing devices appear in the /sys/block/ hierarchy, so I can create 
the device nodes by udevadm test. I created a new init script with 
basically these commands, that activates all the devices:

		for disk in /sys/block/sd*
		do
			udevadm test /block/${disk#/sys/block/}
		done
		
		for part in /sys/block/sd*/sd*
		do
			udevadm test /block/${part#/sys/block/}
		done

Another thing I am missing is the /dev/vg/lvm entries, but I can also 
access the LVM volumes as /dev/mapper/vg-lvm, so this is no problem. But I 
wonder what else is missing that I do not know of yet. And I would prefer 
a real solution over this hack, so if anyone has any ideas, I'd be happy 
to hear them.

	Wonko