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Issue with IDE drives and Instances [closed]

asked 2013-11-18 09:46:05 -0500

Mike77 gravatar image

I know this has been asked many times here, but I have not seen a real solution. I am having problems attaching a volume to an instance in Openstack. I am creating an Instance using a Centos iso file as my base. Once the VM is built whenever I attempt to attach a volume to the instance it always defaults to dev hdx x being whatever letter I assign to it. I am usually trying to mount the drive as either dev vdc or dev vdd. If I use a qcow image that I download I can usually attach the drive without a problem. Right now it appears to only be doing this with the builds I am doing from ISO which is odd. Is there some place you define the hardware types I did build this with the packstack script so I am wondering if I missed something with configurations. Still a newb to Openstack but learning alot. Just need some help over some hurdles

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Closed for the following reason the question is answered, right answer was accepted by koolhead17
close date 2014-08-10 17:22:05.838666

3 answers

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answered 2013-11-18 14:49:40 -0500

Mike77 gravatar image

A possible solution? I stumbled across something about libvirt_type in the /etc/nova/nova.conf file. I changed that from kvm to qemu and rebooted the whole suite. Once I did that, I could mount some previously created volumes to previously created instances without a problem. Of course with QEMU the perforamce is pretty poor compared to that of KVM. I switched my libtype back to KVM, and reboot the stack and the Instances still maintained a connection to the volume. So not sure if its really a solution, but I am interested as to why the KVM seems to default to making everything attached to an instance fail over to IDE. I swear I am not making this up.

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answered 2013-11-19 03:39:56 -0500

Anand TS gravatar image

If you installed openstack using packstack, by default we can see a volume group named cinder volumes with size 20GB.
you just try to create a logical volume less than 20GB (From dashboard->volumes-->create volume) and attach this volume while launching linux vm (CentOS), It takes this as a virtual volume and boot. It should definitely work in this scenario.

But In my case I want to increase this volume size from 20 to a larger size. Is that possible? I didn't create any lvm at the time of installation on my host machine (Centos6.4). If so pls reply.

Regards, Anand

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Sorry I have been away from the board for a while... What I did for a larger size was relatively simple, but not sure its the true way of doing it. Basically I tarred up the /var/lib/nova folder, mounted or linked a larger space to it and then untarred the file.

Mike77 gravatar imageMike77 ( 2013-11-24 16:06:54 -0500 )edit

answered 2013-11-22 01:41:29 -0500

arminder gravatar image

If you create an instance with ISO attached, the same is added as IDE and so later if you add any further volume to that instance it tries to mount that too as IDE and hence hdx, but since IDE doesn't support hot-plugging, so it fails. In such a case I edit my libvirt.xml for that instance and remove drive record info for hda and then reboot my instance. Post that I can add any number of volumes without any issue.

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Cool! I will have to give it a try. I thought I did this and then my Instance would not reboot. Then again maybe I did something else. Appreciate the help!

Mike77 gravatar imageMike77 ( 2013-11-24 16:08:59 -0500 )edit

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Asked: 2013-11-18 09:46:05 -0500

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Last updated: Nov 22 '13