[nova] Rescue booting on wrong disk

Sean Mooney smooney at redhat.com
Tue Feb 9 12:23:58 UTC 2021


On Tue, 2021-02-09 at 11:21 +0000, Arnaud Morin wrote:
> Hey all,
> 
> From time to time we are facing an issue when puting instance in rescue
> with the same image as the one the instance was booted.
> 
> E.G.
> I booted an instance using Debian 10, disk are:
> 
> debian at testarnaud:~$ lsblk
> NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
> sr0     11:0    1  486K  0 rom  
> vda    254:0    0   10G  0 disk 
> └─vda1 254:1    0   10G  0 part /
> debian at testarnaud:~$ cat /etc/fstab 
> # /etc/fstab: static file system information.
> UUID=5605171d-d590-46d5-85e2-60096b533a18	/	ext4
> errors=remount-ro	0	1
> 
> 
> 
> I rescued the instance:
> $ openstack server rescue --image bc73a901-6366-4a69-8ddc-00479b4d647f testarnaud
> 
> 
> Then, back in the instance:
> 
> debian at testarnaud:~$ lsblk
> NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
> sr0     11:0    1  486K  0 rom  
> vda    254:0    0    2G  0 disk 
> └─vda1 254:1    0    2G  0 part 
> vdb    254:16   0   10G  0 disk 
> └─vdb1 254:17   0   10G  0 part /
> 
> 
> 
> Instance booted on /dev/vdb1 instead of /dev/vda1
> 
> Is there anything we can configure on nova side to avoid this
> situation?
in ussuri lee yarwood added https://specs.openstack.org/openstack/nova-specs/specs/ussuri/implemented/virt-rescue-stable-disk-devices.html
to nova which i belive will resolve the issue

from ocata+ i think you can add hw_rescue_bus=usb to get a similar effect but from ussuri we cahgne the layout so thtat the rescue disk is always
used. lee is that right?


> 
> 
> Thanks
> 
> 





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