前言
因爲虛擬機業務的撤銷，compute上面的instance越來越少，隨着虛擬機的遷移和下線，compute節點可能處於資源空閒的狀態，爲了進一步利用系統資源，節約成本，需要將空閒的計算節點從openstack中刪除。在刪除compute節點之前，首先需要確保該計算節點上沒有業務，可以通過virsh list --all查看是否還有虛擬機業務，同時保守起見，建議將compute節點的服務關閉關閉，通過service openstack-nova-compute stop && chkconfig openstack-nova-compute off。
2. 刪除nova計算節點
openstack建議在刪除nova節點的時候，建議通過操作nova.instances中的deleted字段來實現，而不是直接將compute節點的條目從數據庫中刪除，一來是爲了安全考慮，而是能夠實現快速的回滾操作，具體的操作如下：
校驗nova-compute的狀態
[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 | - | #已經處於down的狀態 | nova-compute | YiZhuang_10_1_112_106 | YiZhuangZone2 | enabled | up | 2016-01-20T04:12:24.000000 | - |
2. 刪除compute service節點
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'; #設置deleted字段，即標誌位 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'; #檢查deleted字段設置情況 +---------------------+---------------------+------------+----+-----------------------+--------------+---------+--------------+----------+---------+-----------------+ | 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. 確認節點的service狀態
[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已經刪除
4. 查看hypervisor情況
[root@controller ~]# nova hypervisor-list +----+-----------------------+ | ID | Hypervisor hostname | +----+-----------------------+ | 25 | YiZhuang_10_1_112_105 | #services已經刪除，但hypervisor依舊在，類似的方法，將nova.compute_nodes中的deleted字段修改，查看步驟5 | 27 | YiZhuang_10_1_112_106 |
5. 刪除compute_nodes節點
mysql> update nova.compute_nodes set deleted=1 where hypervisor_hostname='YiZhuang_10_1_112_105'\G; #設置deleted標誌位
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; #確認設置情況
*************************** 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 #設置成功
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. 確認hypervisor node是否刪除
[root@controller ~]# nova hypervisor-list #YiZhuang_10_1_112_105已被刪除 +----+-----------------------+ | ID | Hypervisor hostname | +----+-----------------------+ | 27 | YiZhuang_10_1_112_106 |
3. 刪除neutron agent服務
以上將nova的service和hypervisor從數據庫中刪除，但是compute節點在安裝過程中，neutron-openvswitch-agent會建立一個OVS的agent，該agent也記錄在數據庫中，通過neutron agent-list可以查看到agent的情況，當compute node刪除之後，neutron也應該刪除，方法和上面相類似，具體如下：
確認agent的情況
[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 | #計算節點已經關閉，所以agent狀態變爲xxx，即不可用,:-）可用 | 6a9e2647-6eed-459d-8f60-e9ea40ae04df | Open vSwitch agent | YiZhuang_10_1_112_106 | :-) | True |
2. 刪除OVS agent
mysql> select * from neutron.agents where host='YiZhuang_10_1_112_105'\G; #沒有deleted標誌位，所以只能從數據庫中刪除
*************************** 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; #刪除
Query OK, 1 row affected (0.00 sec)
校驗：
[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. 總結
以上是將compute_nodes從opentack中刪除的方法，在Juno以上的版本，可以通過nova service-delete <hostname> 的方式將compute nodes刪除，在Icehouse以下的版本，暫時未能提供，解決的方法可以通過調用nova db的api，將其刪除，後續再補充。或者通過編寫的腳本的方式，也可以實現，建議通過調用API的方式，直接修改數據庫，而不建議直接修改數據庫的方法。