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On 05/14/2013 11:03 AM, Joe Topjian wrote:
> Hello,
>
> I thought I would post this due to the frequent Gluster talk on the list:
>
> Just an FYI for anyone thinking of using this volume driver: make sure you
> are using a kernel greater than 3.3. For Ubuntu 12.04, the 3.4 kernel found
> here works:
> http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.4-precise/
>
> The reason for this is that Nova tries to attach the volume using
> cache="none". This requires the filesystem to support O_DIRECT, which is
> only available for FUSE-based filesystems in kernels above 3.3.
>
> When trying to attach a gluster-based volume to an instance on a compute
> node that runs a kernel below 3.3 (eg the stock Ubuntu 12.04 kernel), you
> will get a very helpful error message of "DeviceIsBusy: The supplied device
> (vdx) is busy)"...
>
> Hopefully this saves someone the 2 hours of troubleshooting that I went
> through to figure out the real answer  :)
>
> This morning I went to file a bug and saw one has already filed:
> https://bugs.launchpad.net/nova/+bug/1177103
>
> I love when that happens when you already know the answer you're looking
> for  :)
>
> I will also be amending the Gluster volume driver docs to note this.
>
> Finally, this issue seems to be resolved for using Gluster as an instance
> store. If I remember right, I ran into this same issue several months ago
> and it was resolved by updating the kernel. Seems like Grizzly correctly
> detects if O_DIRECT is available or not.
>
> Thanks,
> Joe
>
>

Joe,

Thanks for posting this, and for the doc submission.  (I'll look it over.)

Fixing this properly in Nova is on my to-do list.  It is correct that it 
works for the Nova instance store, the problem is just for Cinder volumes.

Thanks,
Eric


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