OpenStack Compute (nova)

euca-attach-volume gives the wrong drive letter

Asked by Yun Mao

In a tandard devstack installation, I was using the command to attach a volume to /dev/vdc, but it did show up in the instance as /dev/vdb instead. Is the drive letter respected? Thanks.

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David Kranz
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Best David Kranz (david-kranz) said : 		#1

From http://docs.openstack.org/diablo/openstack-compute/admin/content/managing-volumes.html#d654e2376:

If you are using KVM as your hypervisor, then the actual device name in the guest will be different than the one specified in the euca-attach-volume command. You can specify a device name to the KVM hypervisor, but the actual means of attaching to the guest is over a virtual PCI bus. When the guest sees a new device on the PCI bus, it picks the next available name (which in most cases is /dev/vdc) and the disk shows up there on the guest.

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Yun Mao (yunmao) said : 		#2

Thanks David Kranz, that solved my question.