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When you request a volume be attached to /dev/vdX what actually happens on all host Hypervisors except Xen is that the device is assigned to the next available letter in the guest - effectively the auto-assignment logic is always in effect.

What this means is practice is if your guest has a /dev/vda device already, and you request /dev/vdc, the device will actually be assigned to /dev/vdb in spite of your request. Perhaps this is why the volume is not where you expect it to be?

Note that you can also access the volumes using disk-by-id on recent versions of Cinder/Nova, so the volumes can be found at /dev/disk/by-id/virtio-ID where ID is replaced by a subset of the identifier of the volume as shown in the output of cinder list.

https://bugs.launchpad.net/nova/+bug/1004328 http://www.mail-archive.com/openstack@lists.launchpad.net/msg15593.html https://access.redhat.com/site/documentation/en-US/Red_Hat_OpenStack/3/html/Getting_Started_Guide/ch07s06.html

When you request a volume be attached to /dev/vdX what actually happens on all host Hypervisors except Xen is that the device is assigned to the next available letter in the guest - effectively the auto-assignment logic is always in effect.

What this means is practice is if your guest has a /dev/vda device already, and you request /dev/vdc, the device will actually be assigned to /dev/vdb in spite of your request. Perhaps this is why the volume is not where you expect it to be?

Note that you can also access the volumes using disk-by-id on recent versions of Cinder/Nova, so the volumes can be found at /dev/disk/by-id/virtio-ID where ID is replaced by a subset of the identifier of the volume as shown in the output of cinder list.

https://bugs.launchpad.net/nova/+bug/1004328 http://www.mail-archive.com/openstack@lists.launchpad.net/msg15593.html http://www.mail-archive.com/openstack@lists.launchpad.net/msg15593.html https://access.redhat.com/site/documentation/en-US/Red_Hat_OpenStack/3/html/Getting_Started_Guide/ch07s06.html

When you request a volume be attached to /dev/vdX what actually happens on all host Hypervisors except Xen is that the device is assigned to the next available letter in the guest - effectively the auto-assignment logic is always in effect.

What this means is practice is if your guest has a /dev/vda device already, and you request /dev/vdc, the device will actually be assigned to /dev/vdb in spite of your request. Perhaps this is why the volume is not where you expect it to be?

Note that you can also access the volumes using disk-by-id on recent versions of Cinder/Nova, so the volumes can be found at /dev/disk/by-id/virtio-ID where ID is replaced by a subset of the identifier of the volume as shown in the output of cinder list.

https://bugs.launchpad.net/nova/+bug/1004328 https://bugs.launchpad.net/nova/+bug/1004328

http://www.mail-archive.com/openstack@lists.launchpad.net/msg15593.html

https://access.redhat.com/site/documentation/en-US/Red_Hat_OpenStack/3/html/Getting_Started_Guide/ch07s06.html