OpenStack Compute (nova)

Access denied to /sys/hypervisor/uuid

Asked by chris grigg

Folsom in both Ubuntu 12.04 and 12.10 with XCP 1.6 beta 2.

I get access denied errors when I try to do anything with /sys/hypervisor/uuid and as a result, compute will not stat. I've spent all day researching and came up empty. It seems that the very first time I power on a new VM, I'm able to read it with cat. Once I reboot, no go. Checked permissions, running as su. I am completely stuck right now. I can access the type file that's in the same folder.

Any help?

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Mohammed Naser (mnaser) said : 		#1

Just ran into this (funny you wrote this an hour ago). It doesn't really seem related to OpenStack, maybe a Kernel issue?

I solved it by fully shutting down the VM running nova-compute and then starting it again (reboot didn't work). Might be related to reboots, but a full shutdown and start up definitely fixes it.

I'd be interested to see why it's doing that now...

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John Garbutt (johngarbutt) said : 		#2

Turns out you hit this bug if you reboot the VM from inside or outside. If you shutdown and restart then you don't get the issue.

This should be raised against the Ubuntu package I guess, but looks a lot like a PV ops kernel issue (probably on the guest side). I will try look into this for you.

https://bugs.launchpad.net/ubuntu/+source/xen-api/+bug/1081182

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Bob Ball (bob-ball) said : 		#3

there is a workaround to get the UUID until the bug is fixed in XAPI:

root@ubuntulucidlynx1004:~# xenstore-read domid
2
root@ubuntulucidlynx1004:~# xenstore-read /local/domain/2/vm
/vm/6fddd486-b376-647d-d7d4-9acf0e164722

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