[openstack-dev] [nova][cinder][qa] Volume attachment not visible on the guest

Attila Fazekas afazekas at redhat.com
Mon Aug 18 12:05:55 UTC 2014

Hi All,

I have a `little` trouble with the volume attachment stability.

The test_stamp_pattern test is skipped since long, you
can see what would happen if it would be enabled [1] now.

There is a workaround kind way for enabling that test [2].

I suspected the acpi hot plug event is not detected by the kernel 
at some phases of the boot, for example after the first pci scan,
 but before the pci hot plug initialized.

Is the above blind spot really exists ?

If yes, is something what needs to be handled by init system or
 kernel needs to ensure all device is discovered before calling init ?

Long time ago I had trouble with reproducing the above issue,
but now I was able to see a PCI rescan can solve the issue.
'echo "1" > /sys/bus/pci/rescan' (ssh to guest)

Recently we found `another type` of volume attachment issue,
when booting from volume. [3]

Here I would expect the PCI device is ready before,
the VM actually started, but according to the 
console log, the disk device is missing.

When I am booting from an iscsi volume, is the virtual device show up
guaranteed by nova/cinder/libvirt/qemu/whatever
 to be present at the first pci scan ?

Is there anything what can delay the device/disk appearance ?

Best Regards,

[1] https://review.openstack.org/#/c/52740/
[2] https://review.openstack.org/#/c/62886/
[3] https://bugs.launchpad.net/nova/+bug/1357677

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