Host Evacuate Deleted disk Files and Rebuilt VMs

Problem

When an evacuate operation is performed on a host, the disk files are deleted and the VMs are rebuilt using the image.

Environment

• Platform9 Managed OpenStack - v3.6.0 and higher
• Nova
• NFS v3

Cause

• Since libvirt does not have a rebuilt function, the spawn function is called by Nova compute service.
• The spawn function for the libvirt driver destroys disk if it fails to launch an instance.

self._create_domain_and_network(            context, xml, instance, network_info,            block_device_info=block_device_info,            post_xml_callback=gen_confdrive,            destroy_disks_on_failure=True)        LOG.debug("Guest created on hypervisor", instance=instance)

• The disk files are deleted because libvirt fails to get a write lock on the disk file and the instance fails to get created after which Nova rebuilds the instance using the original image.

Resolution

1. Add the nolock option to the NFS mount options in the nova_override.conf file located under /opt/pf9/etc/nova/conf.d directory.

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[libvirt]nfs_mount_options = vers=3,nolock

2. Restart pf9-ostackhost service on the host.

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# sudo systemctl restart pf9-ostackhost

Additional Information

https://bugzilla.redhat.com/show\_bug.cgi?id=1547095