08.存储Cinder→5.场景学习→04.Detach Volume

背景：

注意，这个文件中的volume都是已经被attach了的，没有attach的volume不会在这个文件夹(针对lvm是这样，但nfs不是)

描述

详细

向 cinder-api 发送 detach 请求

客户（可以是 OpenStack 最终用户，也可以是其他程序）向 cinder-api 发送请求：“请 detach 指定 instance 上的 volume。”
这里我们将 detach instance “c1”上的 volume “vol-1” 进入 GUI 操作菜单Project -> Volumes -> Volumes。选择 volume “vol-1”，点击“Manage Attachments”。点击 “Detach Volume”。

查看cinder-api日志

Jun 20 17:05:32 controller devstack@c-api.service[31309]: 

INFO cinder.api.openstack.wsgi 

[req-8db7c86d-8c94-42bc-a2cd-923051715351 req-7... admin admin] 

POST http://172.16.1.17/volume/v3/51743f081cb7477f9a1f4ccdf6490d8e

/volumes/f0a54ac7-5423-4794-8883-d753f6a903cd/action

Jun 20 17:05:32 controller devstack@c-api.service[31309]: 

DEBUG cinder.api.openstack.wsgi 

[req-8db7c86d-8c94-42bc-a2cd-923051715351 req-... admin admin] 

Action body: {"os-begin_detaching": null} 

{{(pid=31313) get_method /opt/stack/cinder/cinder/api/openstack/wsgi.py:985

cinder-api 发送消息

cinder-api 发送消息 detach 消息。cinder-api 没有打印发送消息的日志，只能通过源代码查看 /opt/stack/cinder/cinder/volume/api.py，方法为 detach。

nova-compute detach volume

查看计算节点上的n-cpu日志

Jun 20 17:05:33 compute nova-compute[5685]: 

INFO nova.compute.manager 

[None req-8db7c86d-8c94-42bc-a2cd-923051715351 admin admin] 

[instance: 0af39618-5d8c-4fc8-bb44-781246bff6dd] 

Detaching volume f0a54ac7-5423-4794-8883-d753f6a903cd

调用os-brick模块来detach volume

Jun 20 17:05:33 compute nova-compute[5685]: 

DEBUG nova.virt.libvirt.volume.iscsi 

[None req-8db7c86d-8c94-42bc-a2cd-923051715351 admin admin] 

[instance: 0af39618-5d8c-4fc8-bb44-781246bff6dd] calling os-brick to detach iSCSI Volume 

{{(pid=5685) disconnect_volume /opt/stack/nova/nova/virt/libvirt/volume/iscsi.py:72}

具体有下面几个步骤：

将缓存中的数据 Flush 到 volume

Jun 20 17:05:33 compute nova-compute[5685]: 

DEBUG os_brick.initiator.linuxscsi 

[None req-8db7c86d-8c94-42bc-a2cd-923051715351 admin admin] 

Flushing IO for device /dev/sda {{(pid=5685)

flush_device_io /usr/local/lib/python2.7/dist-packages/os_brick/initiator/linuxscsi.py:313

target vdb的souce是/dev/sda，就是要 attach 的 volume参考见08.存储Cinder→5.场景学习→3.Attach Volume→2.实际操作

删除计算节点上 volume 对应的 SCSI 设备sda

Jun 20 17:05:33 compute nova-compute[5685]: 

DEBUG os_brick.initiator.linuxscsi 

[None req-8db7c86d-8c94-42bc-a2cd-923051715351 admin admin] 

Remove SCSI device /dev/sda with /sys/block/sda/device/delete 

{{(pid=5685) remove_scsi_device /usr/local/lib/python2.7/dist-packages/os_brick/initiator/linuxscsi.py:76

Jun 20 17:05:33 compute nova-compute[5685]: 

DEBUG os_brick.initiator.linuxscsi 

[None req-8db7c86d-8c94-42bc-a2cd-923051715351 admin admin] 

Checking to see if SCSI volumes sda have been removed. 

{{(pid=5685) wait_for_volumes_removal /usr/local/lib/python2.7/dist-packages/os_brick/initiator/linuxscsi.py:84

Jun 20 17:05:33 compute nova-compute[5685]: 

DEBUG os_brick.initiator.linuxscsi 

[None req-8db7c86d-8c94-42bc-a2cd-923051715351 admin admin] 

SCSI volumes sda have been removed. 

{{(pid=5685) wait_for_volumes_removal /usr/local/lib/python2.7/dist-packages/os_brick/initiator/linuxscsi.py:93

通过 iscsiadm 的 logout，delete 操作断开与 iSCSI target 的连接

Jun 20 17:05:33 compute nova-compute[5685]: 

DEBUG os_brick.initiator.connectors.iscsi 

[None req-8db7c86d-8c94-42bc-a2cd-923051715351 admin admin] 

iscsiadm ('--logout',): stdout=Logging out of session ...

Jun 20 17:05:33 compute nova-compute[5685]: 

DEBUG os_brick.initiator.connectors.iscsi 

[None req-8db7c86d-8c94-42bc-a2cd-923051715351 admin admin] 

iscsiadm ('--op', 'delete'): stdout= stderr= 

{{(pid=5685) _run_iscsiadm /usr/local/lib/python2.7/dist-packages/os_brick/initiator/connectors/iscsi.py:973

cinder-volume 删除 target

存储节点 cinder-volume 通过 tgt-admin 命令删除 volume 对应的 target。查看c-vol日志

Jun 20 17:05:34 controller cinder-volume[304]: 

INFO cinder.volume.targets.tgt 

[req-8db7c86d-8c94-42bc-a2cd-923051715351 req-47b18f6e-2c48-4977-ac20-803ff3125bd5 admin None] 

Removing iscsi_target for Volume ID: f0a54ac7-5423-4794-8883-d753f6a903cd

Jun 20 17:05:34 controller cinder-volume[304]: 

DEBUG oslo_concurrency.processutils 

[req-8db7c86d-8c94-42bc-a2cd-923051715351 req-47b18f6e-2c48-4977-ac20-803ff3125bd5 admin None] 

CMD "sudo cinder-rootwrap /etc/cinder/rootwrap.conf tgt-admin --force --delete 

iqn.2010-10.org.openstack:volume-f0a54ac7-5423-4794-8883-d753f6a903cd" returned: 0 in 0.273s 

{{(pid=460) execute /usr/local/lib/python2.7/dist-packages/oslo_concurrency/processutils.py:409

至此 detach volume 操作已经完成，GUI 也会更新 volume 的 detach 信息

通过在计算节点输入virsh edit instance-00000001查看更新后的 XML，发现/dev/vdb设备已经删除

08.存储Cinder→5.场景学习→04.Detach Volume

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