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Hi, Changqian:

I think it's better to try using the corresponding detach command of libvirt (virsh detach-disk or virsh detach-device) first, and see if the behavior is expected.



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Leiqzhang

Best Regards

From: Zuo Changqian [mailto:dummyhacker85 at gmail.com]
Sent: Wednesday, February 26, 2014 3:49 PM
To: Gangur, Hrushikesh (R & D HP Cloud)
Cc: Openstack at lists.openstack.org
Subject: Re: [Openstack] [Nova] KVM Windows Guest disk hot plugging support.

By the way, it's Havana release.
We first found this problem in Ubuntu 12.04 LTS guest, after loading "acpiphp" kernel module at instance boot time, the problem solved.
Then we tested using CentOS 6.x guest, it seems the code of "acpiphp" module has been integrated into Linux kernel at compilation time. Nothing needs to been done, it just works very well. You can freely attach and detach volumes when instance is running.
But this does not work for Windows guest, you can attach volumes, and you can detach, but it seems still some information of disk remain in Windows guest, and you can not attach a second time.
A reboot do cleanup those remained infomation, and we know this. I am wondering if this attach/detach can be all done when Windows guest is running, just like it is done in Linux guest.


2014-02-26 15:07 GMT+08:00 Gangur, Hrushikesh (R & D HP Cloud) <hrushikesh.gangur at hp.com<mailto:hrushikesh.gangur at hp.com>>:
I have seen this issue on Linux VMs too. A reboot of the VM instance helps workaround this.

From: Zuo Changqian [mailto:dummyhacker85 at gmail.com<mailto:dummyhacker85 at gmail.com>]
Sent: Tuesday, February 25, 2014 10:34 PM
To: Openstack at lists.openstack.org<mailto:Openstack at lists.openstack.org>
Subject: [Openstack] [Nova] KVM Windows Guest disk hot plugging support.

Hi

Currently we use Cpeh RBD as cinder volume. According to http://www.linux-kvm.org/page/Hotadd_pci_devices, we have Linux KVM guest (both CentOS 6.x and Ubuntu 12.04) support disk hot plugging, it works well.
But there is problem with Windows 2008 guest (2003 not tested). Described below:

1) Launch an Windows 2008 instance (with RedHat Virtio Driver installed), and attach a volume (newly created with nothing inside) to it, the volume would be successfully attached to /dev/vdb.
2) In Windows (guest machine), format this newly added disk. After formatting, it will show up in "My Computer" windows. Create any file (readme.txt with some text in it for example) inside the new disk. Then deatch the volume.

After about one or two minute, a message box would show up in Windows, saying that the device not properly removed, and the newly added disk would still show in "My Computer" window. But with "cinder list" command, we can see that the volume was successfully detached.

3) Now reattach to volume to instance, it would failed.

Libvirt log shows:
error : qemuMonitorJSONCheckError:357 : internal error unable to execute QEMU command '__com.redhat_drive_add': Duplicate ID 'drive-virtio-disk1' for drive
I googled yesterday afternoon, didn't find useful information. Would any one tell me whether Windows 2003/2008 as kvm fully virtualized guest supports disk hot plugging and removing or not? Or any possibility I have got something wrong?

Thanks for help!

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