** Also affects: nova/icehouse
Importance: Undecided
Status: New
** Changed in: nova/icehouse
Status: New => In Progress
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https://bugs.launchpad.net/bugs/1305423
Title:
nova libvirt re-write broken with mulitiple ephemeral disks
Status in OpenStack Compute (Nova):
Fix Released
Status in OpenStack Compute (nova) icehouse series:
In Progress
Bug description:
Seem to be experiencing a bug with libvirt.xml device formatting when
--ephemeral flag is used after initial booth and then use of nova stop/start or
nova reboot --hard. We are using following libvirt options in nova.conf for
storage:
libvirt_images_type=lvm
libvirt_images_volume_group=vglocal
When normally using nova boot with a flavor that has ephemeral defined it
create two LVM volumes appropriatly ex.
instance-0000077e_disk
instance-0000077e_disk.local
The instance libvirt.xml contains disk devices entry as follows:
<devices>
<disk type="block" device="disk">
<driver name="qemu" type="raw" cache="none"/>
<source dev="/dev/vgephemeral/instance-0000077e_disk"/>
<target bus="virtio" dev="vda"/>
</disk>
<disk type="block" device="disk">
<driver name="qemu" type="raw" cache="none"/>
<source dev="/dev/vgephemeral/instance-0000077e_disk.local"/>
<target bus="virtio" dev="vdb"/>
</disk>
If we use "nova boot --flavor 757c75fa-0b6d-4d4f-a128-27813009bff4 --image
caa978e0-acae-4205-a4a4-2cf159c166fd --nic
net-id=44f2fb0b-0a7a-475c-8fff-54cd4b37958b --ephemeral size=1 --ephemeral
size=1 localdisk-1" the LVM disks for ephemeral goes through enumeration logic
whether there is one or more --ephemeral options
instance-000007ed_disk
instance-000007ed_disk.eph0
instance-000007ed_disk.eph1
The instance libvirt.xml after instance spawn has disk device entries like
below and the instances happily boots.
<devices>
<disk type="block" device="disk">
<driver name="qemu" type="raw" cache="none"/>
<source dev="/dev/vgephemeral/instance-000007ed_disk"/>
<target bus="virtio" dev="vda"/>
</disk>
<disk type="block" device="disk">
<driver name="qemu" type="raw" cache="none"/>
<source dev="/dev/vgephemeral/instance-000007ed_disk.eph0"/>
<target bus="virtio" dev="vdb"/>
</disk>
<disk type="block" device="disk">
<driver name="qemu" type="raw" cache="none"/>
<source dev="/dev/vgephemeral/instance-000007ed_disk.eph1"/>
<target bus="virtio" dev="vdc"/>
</disk>
If nova stop/start or nova reboot --hard is executed the instance is
destroyed and libvirt.xml gets recreated. At this stage whatever values we
passed with --ephemeral are not respected and libvirt.xml revirts to
configuration that would have been generated without the use of the --ephemeral
option like below where we only have one extra disk and it is not using the
enumerated naming.
<devices>
<disk type="block" device="disk">
<driver name="qemu" type="raw" cache="none"/>
<source dev="/dev/vgephemeral/instance-000007ed_disk"/>
<target bus="virtio" dev="vda"/>
</disk>
<disk type="block" device="disk">
<driver name="qemu" type="raw" cache="none"/>
<source dev="/dev/vgephemeral/instance-000007ed_disk.local"/>
<target bus="virtio" dev="vdb"/>
</disk>
This causes instances booting to fail at this stage. The nova
block_device_mapping table has records for all 3 devices.
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