Open Stack

Hello All,

This is regarding bug https://launchpad.net/bugs/1667269 titled as Nova volume-attach doesn't care for device name
Review is going on at https://review.openstack.org/#/c/454048/

Description:
[root at greglinux2 ~(keystone_admin)]# nova volume-attach e9c63adc-e837-4108-b5cf-10a8f147a5ab f0990f38-8fc5-4710-b9ac-e846b6c634cb /dev/vdc >>>
+----------+--------------------------------------+
| Property | Value |
+----------+--------------------------------------+
| device | /dev/vdb | >>>>> Still attached as /dev/vdb !!!! >>>>>>>>>>>>>>>>>>.
| id | f0990f38-8fc5-4710-b9ac-e846b6c634cb |
| serverId | e9c63adc-e837-4108-b5cf-10a8f147a5ab |
| volumeId | f0990f38-8fc5-4710-b9ac-e846b6c634cb |
+----------+--------------------------------------+

It looks like nova is not considering <device> parameter at all. Is it expected?
It shows that "/dev/vdc" was requested by client as device name but server prefers to ignore it.

As seen in nova server side logs :
====================================

2017-04-05 03:35:58.902 3199 WARNING nova.virt.libvirt.driver [req-90bfc957-2cb2-47e4-9018-fb0e24404f7b c2a01ca6f6f84d388dbd12c68eaa1d13 f29439bb99d54dba980631b1ef7bd8cd - - -] [instance: 31aaa8e3-3163-4f17-8ccd-f22c3c35ce95] Ignoring supplied device name: /dev/vdr >>>>>>>>>>>>>>>>>>>>>>>>>>

2017-04-05 03:35:58.903 3199 WARNING nova.virt.osinfo [req-90bfc957-2cb2-47e4-9018-fb0e24404f7b c2a01ca6f6f84d388dbd12c68eaa1d13 f29439bb99d54dba980631b1ef7bd8cd - - -] Cannot find OS information - Reason: (No configuration information found for operating system Empty)

2017-04-05 03:35:59.312 3199 INFO nova.compute.manager [req-90bfc957-2cb2-47e4-9018-fb0e24404f7b c2a01ca6f6f84d388dbd12c68eaa1d13 f29439bb99d54dba980631b1ef7bd8cd - - -] [instance: 31aaa8e3-3163-4f17-8ccd-f22c3c35ce95] Attaching volume 657ed918-36ae-4ffc-a08b-275eefd0c152 to /dev/vde >>>>>>>>>>>>>>>>>>>>>>.

Where in code file
nova/virt/libvirt/drivers.py

we see that if a device name is not none intentionally we ignore the device name coming from cli.

Hence i think in that case there is no use of sending device name from novaclient.

As we are just confusing user by asking him device name and later ignoring it intentionally.

Hence we fixed it by removing device name option from shell.py in novaclient.



But there are opinion which differ like

Matt Riedemann says



"I think I'd like to see this brought up in the openstack-dev mailing list http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev or at least the weekly nova team meeting [1] to make sure everyone is on the same page before doing this, because the libvirt driver is technically the only one that ignores the requested device, not all drivers do that.

And I tried deprecated block device name from the API but that ran into complications:

https://review.openstack.org/#/c/452546/

[1] https://wiki.openstack.org/wiki/Meetings/Nova "



Can wider audience with your experience please share your thoughts on this?



Thanks

Nidhi







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