Some tips for performing smooth maintenance in OpenStack.
Maintenance can define a lot of actions:
- Hardware upgrade
- Security patch
- Update and reboot
Obviously one day, everyone (or good sysadmin) needs to reboot a server.
Several setup and scenario:
- VM disks are stored on a distributed filesystem (cephFS, glusterFS, NFS…). Easy to perform a maintenance.
- VM disks are stored locally, this is the most difficul part.
II. Put a node into maintenance
There is already a maintenance mode, but the feature has been implemented only for Xen hypervisor, if you run KVM and you issue the following command, you will get an error, which is obvious:
As a workaround you could:
- Specify a different location for the new instances. But you can only do this if you manage your Cloud.
- Disable a compute node
II.1. Private cloud approach
You can use the following command to force the run on a specific node:
R Note: admin permissions are required. and the default zone is
II.2. Public Cloud approach
Even better I guess, you could disable the compute node from the service, thus nova-scheduler won’t attemps to run any instance on this compute node.
Hope it helps! If someone has another method, please share ;-).