How can I force the instance to mount a volume as different device?

asked 2014-08-27 08:25:57 -0600

Piotr gravatar image

updated 2014-08-29 18:02:13 -0600

smaffulli gravatar image

Hello I have a quite strange problem with attached volume. I have one volume in cinder, one instance and I'm trying to attach this volume as a drive /dev/vdd to the instance. I'm using the command:

nova volume-attach test123 caa842b2-efee-4d80-a342-d5310cd168a2 /dev/vdd

But the dmesg on instance shows that the volume is attached as vdb. nova volume show shows :

| attachments                    | [{"device": "/dev/vdd", "server_id": "5fe3ca19-07ed-4e0b-9f0f-ed5a57704cde", "volume_id": "caa842b2-efee-4d80-a342-d5310cd168a2", "host_name": null, "id": "caa842b2-efee-4d80-a342-d5310cd168a2"}] |

How can I force the instance to use this volume as vdd not vdb? I can write some udev rules or make a link to this device but IMHO the instance should use the device name provided by nova volume-attach command.

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See if it does the same when you launch the instance with the volume added as /dev/vdd. It may be due to metadata. I know that whenever you hot attach storage it always goes to the next available device. I don't know if you can force KVM to attach it when there isn't vdb vdc already added.

mpetason gravatar imagempetason ( 2014-08-27 12:52:19 -0600 )edit

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answered 2014-09-02 08:43:57 -0600

gmi gravatar image

When you attach a volume, KVM ignores the device name you pass because it does its own naming (this behavior is documented here: )

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Asked: 2014-08-27 08:25:57 -0600

Seen: 1,245 times

Last updated: Sep 02 '14