Openstack Node Maintenance detailed explanation _openstack

OpenStack Introduction

OpenStack is an open source IaaS implementation that consists of a number of interrelated subprojects, including computing, storage, and networking. With the launch of the Apache protocol, more than 200 companies have joined the OpenStack project since its inception in 2010, including At&t, AMD, Cisco, Dell, IBM, Intel, Red Hat and so on. The number of developers currently involved in the OpenStack project is 17,000 +, from 139 countries, and the figure is growing.

OpenStack is compatible with a subset of the AWS interfaces, while providing a OpenStack-style interface (RESTFul API) to provide more powerful functionality. Compared to other open source IaaS, the architecture is loosely coupled, highly scalable, distributed, pure Python implementation, and friendly and active communities make it popular, and every semi-annual development summit attracts developers, suppliers, and customers from around the world.

Openstack Node Maintenance

Motivation to maintain

The main motivation for maintaining a OpenStack node is three points:

1. Hardware replacement or upgrade
2. Reboot required after security patch
3. Software upgrades and service restart

There are generally two scenarios:

1.VM of disk stored on DFS (CEPHFS, Glusterfs, NFS), easy to maintain
2.VM disk stored on local disk, most difficult to maintain

Set a OpenStack node to maintenance mode

There is already maintenance mode in the current OpenStack, but only for Xen hypervisor, and if you are using KVM, you will see a 500 error:

Nova host-update compute-01--maintenance enable
error:the server has either erred or is incapable of performing the Requested operation. (HTTP 500) (REQUEST-ID:REQ-5667D1FF-BGHA-4VEQ-9DRB-8C6 ' 733f1s4b)

As a workaround, you can use the following methods:

1. Point the new instacnes to another location;
2. Disable the COMPUTE node

Solutions for private clouds

Use the following command to force the VM to be created to the specified node, the default zone is Nova:

Nova boot bla bla bla--availability-zone <your-zone>:<compute-node>

Solutions for Public Cloud

Disable the node directly so that scheduler does not attempt to run an instance on that node:

$ sudo nova-manage service disable--host=

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