Glance

Centos Cloud Install

Asked by Peter Borghard

I'm having an issue with a centos 6 base image that I built out for openstack. I used KVM cli and vnc to mount an centos6 iso, install OS, ran updates, etc. I set the '/' partition to low, only a couple of GB. When I try to spawn an instance using flavors, the instance doesn't seem to be resizing to match the size configured in the flavor. I'm currently using the Ubuntu cloud images and they seem to be working perfect when it comes to resizing to match the flavor. Is there anything special that I need to do with Centos? I tried two different methods, centos with logical volumes and without. Neither seemed to work. Any info you have will be helpful.

Thanks,
Peter Borghard

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Jay Pipes (jaypipes) said : 		#1

Make sure you have enough space allocated to the partition/volume that you are using for /tmp. resize2fs and libvirt will error out with Unable to write errors if there is not enough space in /tmp to deal with the resize operation.

Do an:

 sudo ln -s /some/directory/with/space /tmp

if you need to...

-jay

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Peter Borghard (pborghard) said : 		#2

Jay,

Is there a rule of thumb for how big to make the /tmp partition? I don't know if it needs to be relative to size of the instance.

Peter Borghard

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Peter Borghard (pborghard) said : 		#3

Jay,

If I wanted to debug this issue, which log file should I be checking? I was looking through all the nova/glance logs and I don't see any errors.

Thanks,
Peter Borghard

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Jay Pipes (jaypipes) said : 		#4

Hi again, Peter, sorry for delayed response....

You can grep through the nova-compute logs looking for "libvirtError".

The rule of thumb I'm using is that /tmp should just have enough space to be able to complete a resize and/or snapshot operation for the largest flavors that you plan on using on the box. The resize and snapshot operations in KVM uses the qemu-img and resize2fs command line tools, and these tools (AFAIK) set aside an area in /tmp by default to build new images. The space needed depends on how big the images being snapshotted or resized are (in RAM)

Best,
-jay

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