前言
因为虚拟机业务的撤销，compute上面的instance越来越少，随着虚拟机的迁移和下线，compute节点可能处于资源空闲的状态，为了进一步利用系统资源，节约成本，需要将空闲的计算节点从openstack中删除。在删除compute节点之前，首先需要确保该计算节点上没有业务，可以通过virsh list --all查看是否还有虚拟机业务，同时保守起见，建议将compute节点的服务关闭关闭，通过service openstack-nova-compute stop && chkconfig openstack-nova-compute off。
2. 删除nova计算节点
openstack建议在删除nova节点的时候，建议通过操作nova.instances中的deleted字段来实现，而不是直接将compute节点的条目从数据库中删除，一来是为了安全考虑，而是能够实现快速的回滚操作，具体的操作如下：
校验nova-compute的状态
[root@controller ~]# nova service-list +------------------+-----------------------+---------------+---------+-------+----------------------------+-----------------+ | Binary | Host | Zone | Status | State | Updated_at | Disabled Reason | +------------------+-----------------------+---------------+---------+-------+----------------------------+-----------------+ | nova-scheduler | controller | internal | enabled | up | 2016-01-20T04:12:33.000000 | - | | nova-cert | controller | internal | enabled | up | 2016-01-20T04:12:31.000000 | - | | nova-conductor | controller | internal | enabled | up | 2016-01-20T04:12:27.000000 | - | | nova-consoleauth | controller | internal | enabled | up | 2016-01-20T04:12:33.000000 | - | | nova-compute | YiZhuang_10_1_112_105 | YiZhuangZone2 | enabled | down | 2016-01-16T09:11:57.000000 | - | #已经处于down的状态 | nova-compute | YiZhuang_10_1_112_106 | YiZhuangZone2 | enabled | up | 2016-01-20T04:12:24.000000 | - |
2. 删除compute service节点
mysql> select * from nova.services where host='YiZhuang_10_1_112_105'; +---------------------+---------------------+------------+----+-----------------------+--------------+---------+--------------+----------+---------+-----------------+ | created_at | updated_at | deleted_at | id | host | binary | topic | report_count | disabled | deleted | disabled_reason | +---------------------+---------------------+------------+----+-----------------------+--------------+---------+--------------+----------+---------+-----------------+ | 2015-09-21 03:21:40 | 2016-01-16 09:11:57 | NULL | 37 | YiZhuang_10_1_112_105 | nova-compute | compute | 1011705 | 0 | 0 | NULL | +---------------------+---------------------+------------+----+-----------------------+--------------+---------+--------------+----------+---------+-----------------+ 1 row in set (0.00 sec) mysql> update nova.services set deleted=1 where host='YiZhuang_10_1_112_105'; #设置deleted字段，即标志位 Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from nova.services where host='YiZhuang_10_1_112_105'; #检查deleted字段设置情况 +---------------------+---------------------+------------+----+-----------------------+--------------+---------+--------------+----------+---------+-----------------+ | created_at | updated_at | deleted_at | id | host | binary | topic | report_count | disabled | deleted | disabled_reason | +---------------------+---------------------+------------+----+-----------------------+--------------+---------+--------------+----------+---------+-----------------+ | 2015-09-21 03:21:40 | 2016-01-16 09:11:57 | NULL | 37 | YiZhuang_10_1_112_105 | nova-compute | compute | 1011705 | 0 | 1 | NULL | +---------------------+---------------------+------------+----+-----------------------+--------------+---------+--------------+----------+---------+-----------------+ 1 row in set (0.00 sec)
3. 确认节点的service状态
[root@controller ~]# nova service-list +------------------+-----------------------+---------------+---------+-------+----------------------------+-----------------+ | Binary | Host | Zone | Status | State | Updated_at | Disabled Reason | +------------------+-----------------------+---------------+---------+-------+----------------------------+-----------------+ | nova-scheduler | controller | internal | enabled | up | 2016-01-20T04:12:33.000000 | - | | nova-cert | controller | internal | enabled | up | 2016-01-20T04:12:31.000000 | - | | nova-conductor | controller | internal | enabled | up | 2016-01-20T04:12:27.000000 | - | | nova-consoleauth | controller | internal | enabled | up | 2016-01-20T04:12:33.000000 | - | | nova-compute | YiZhuang_10_1_112_106 | YiZhuangZone2 | enabled | up | 2016-01-20T04:12:24.000000 | - | #service已经删除
4. 查看hypervisor情况
[root@controller ~]# nova hypervisor-list +----+-----------------------+ | ID | Hypervisor hostname | +----+-----------------------+ | 25 | YiZhuang_10_1_112_105 | #services已经删除，但hypervisor依旧在，类似的方法，将nova.compute_nodes中的deleted字段修改，查看步骤5 | 27 | YiZhuang_10_1_112_106 |
5. 删除compute_nodes节点
mysql> update nova.compute_nodes set deleted=1 where hypervisor_hostname='YiZhuang_10_1_112_105'\G; #设置deleted标志位
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from nova.compute_nodes where hypervisor_hostname='YiZhuang_10_1_112_105'\G; #确认设置情况
*************************** 1. row ***************************
created_at: 2015-09-21 03:21:40
updated_at: 2016-01-16 09:11:36
deleted_at: NULL
id: 25
service_id: 37
vcpus: 24
memory_mb: 64396
local_gb: 3062
vcpus_used: 0
memory_mb_used: 1024
local_gb_used: 20
hypervisor_type: QEMU
hypervisor_version: 12001
cpu_info: {"vendor": "Intel", "model": "SandyBridge", "arch": "x86_64", "features": ["vme", "dtes64", "vmx", "erms", "xtpr", "smep", "pcid", "est", "monitor", "smx", "tm", "acpi", "osxsave", "ht", "dca", "pdcm", "pdpe1gb", "fsgsbase", "f16c", "ds", "tm2", "ss", "pbe", "ds_cpl", "rdrand"], "topology": {"cores": 6, "threads": 2, "sockets": 1}}
disk_available_least: 2671
free_ram_mb: 63372
free_disk_gb: 3042
current_workload: 0
running_vms: 0
hypervisor_hostname: YiZhuang_10_1_112_105
deleted: 1 #设置成功
host_ip: 0.0.0.0
supported_instances: [["i686", "qemu", "hvm"], ["i686", "kvm", "hvm"], ["x86_64", "qemu", "hvm"], ["x86_64", "kvm", "hvm"]]
pci_stats: []
metrics: []
extra_resources: NULL
stats: {"num_task_None": 2, "io_workload": 0, "num_instances": 2, "num_vm_stopped": 2, "num_proj_a49b16d5324a4d20bde2217b17200485": 2, "num_vcpus_used": 8, "num_os_type_None": 2}
1 row in set (0.00 sec)
6. 确认hypervisor node是否删除
[root@controller ~]# nova hypervisor-list #YiZhuang_10_1_112_105已被删除 +----+-----------------------+ | ID | Hypervisor hostname | +----+-----------------------+ | 27 | YiZhuang_10_1_112_106 |
3. 删除neutron agent服务
以上将nova的service和hypervisor从数据库中删除，但是compute节点在安装过程中，neutron-openvswitch-agent会建立一个OVS的agent，该agent也记录在数据库中，通过neutron agent-list可以查看到agent的情况，当compute node删除之后，neutron也应该删除，方法和上面相类似，具体如下：
确认agent的情况
[root@controller ~]# neutron agent-list +--------------------------------------+--------------------+-----------------------+-------+----------------+ | id | agent_type | host | alive | admin_state_up | +--------------------------------------+--------------------+-----------------------+-------+----------------+ | 0160e0b7-22fb-42d9-8e43-0d13d98db594 | L3 agent | LuGu_10_1_81_209 | :-) | True | | 4e1c9957-98e5-4516-af2d-6c67a00ecd77 | Open vSwitch agent | YiZhuang_10_1_112_105 | xxx | True | #计算节点已经关闭，所以agent状态变为xxx，即不可用,:-）可用 | 6a9e2647-6eed-459d-8f60-e9ea40ae04df | Open vSwitch agent | YiZhuang_10_1_112_106 | :-) | True |
2. 删除OVS agent
mysql> select * from neutron.agents where host='YiZhuang_10_1_112_105'\G; #没有deleted标志位，所以只能从数据库中删除
*************************** 1. row ***************************
id: 4e1c9957-98e5-4516-af2d-6c67a00ecd77
agent_type: Open vSwitch agent
binary: neutron-openvswitch-agent
topic: N/A
host: YiZhuang_10_1_112_105
admin_state_up: 1
created_at: 2015-09-21 03:22:01
started_at: 2016-01-19 09:15:45
heartbeat_timestamp: 2016-01-19 09:15:45
description: NULL
configurations: {"tunnel_types": [], "tunneling_ip": "", "bridge_mappings": {"physnet1": "br-eth1", "physnet0": "br-eth0"}, "l2_population": false, "devices": 0}
1 row in set (0.00 sec)
mysql> delete from neutron.agents where host='YiZhuang_10_1_112_105'\G; #删除
Query OK, 1 row affected (0.00 sec)
校验：
[root@controller ~]# neutron agent-list
+--------------------------------------+--------------------+-----------------------+-------+----------------+
| id | agent_type | host | alive | admin_state_up |
+--------------------------------------+--------------------+-----------------------+-------+----------------+
| 0160e0b7-22fb-42d9-8e43-0d13d98db594 | L3 agent | LuGu_10_1_81_209 | :-) | True |
| 6a9e2647-6eed-459d-8f60-e9ea40ae04df | Open vSwitch agent | YiZhuang_10_1_112_106 | :-) | True |
4. 总结
以上是将compute_nodes从opentack中删除的方法，在Juno以上的版本，可以通过nova service-delete