目录
前言
Cinder 支持 front-end 和 back-end 两种类型的存储 QoS，前者由 Hypervisor 端实现（e.g. 通过 Libvirt 设置虚拟机的存储 QoS），后者指存储设备上设置的 QoS，需要存储设备支持。 一般的物理存储设备都会支持 QoS，但 SDS 的 Ceph RBD 不支持，所以使用 Ceph 存储方案的用户一般只能使用 front-end Qos 来限制虚拟机对数据盘的 Qos。
QoS 项目：
- total_bytes_sec - the total allowed bandwidth for the guest per second
- read_bytes_sec - sequential read limitation
- write_bytes_sec - sequential write limitation
- total_iops_sec - the total allowed IOPS for the guest per second
- read_iops_sec - random read limitation
- write_iops_sec - random write limitation
操作步骤
通过 openstackclient 创建具有 QoS Policy 的 Volume Type：
[stack@manager ~]$ openstack volume type create VolumeType1
+---------------------------------+--------------------------------------+
| Field | Value |
+---------------------------------+--------------------------------------+
| description | None |
| id | ae5359b3-0bbc-4104-88ca-3749eab07cc8 |
| is_public | True |
| name | VolumeType1 |
| os-volume-type-access:is_public | True |
+---------------------------------+--------------------------------------+
[stack@manager ~]$ openstack volume type show VolumeType1
+---------------------------------+--------------------------------------+
| Field | Value |
+---------------------------------+--------------------------------------+
| access_project_ids | None |
| description | None |
| id | ae5359b3-0bbc-4104-88ca-3749eab07cc8 |
| is_public | True |
| name | VolumeType1 |
| os-volume-type-access:is_public | True |
| properties | |
| qos_specs_id | None |
+---------------------------------+--------------------------------------+
[stack@manager ~]$ openstack volume qos create qos1 --consumer front-end --property total_iops_sec=200
+----------+--------------------------------------+
| Field | Value |
+----------+--------------------------------------+
| consumer | front-end |
| id | 05ab9096-3a0f-45d8-acb8-f0cac172ae8c |
| name | qos1 |
| specs | {u'total_iops_sec': u'200'} |
+----------+--------------------------------------+
[stack@manager ~]$ openstack volume qos set --property total_bytes_sec=2048000 qos1
[stack@manager ~]$ openstack volume qos associate qos1 VolumeType1
指定 VolumeType 创建 Volume：
[stack@manager ~]$ openstack volume create --type VolumeType1 --size 1 volume1
+---------------------+--------------------------------------+
| Field | Value |
+---------------------+--------------------------------------+
| attachments | [] |
| availability_zone | nova |
| bootable | false |
| consistencygroup_id | None |
| created_at | 2018-12-26T13:51:22.597699 |
| description | None |
| encrypted | False |
| id | c24e2a9e-1792-4951-a040-434b87409558 |
| migration_status | None |
| multiattach | False |
| name | volume1 |
| properties | |
| replication_status | disabled |
| size | 1 |
| snapshot_id | None |
| source_volid | None |
| status | creating |
| type | VolumeType1 |
| updated_at | None |
| user_id | 11b816e454384d038472c7c89d2544f4 |
+---------------------+--------------------------------------+
[stack@manager ~]$ openstack volume list
+--------------------------------------+--------------+-----------+------+-------------+
| ID | Display Name | Status | Size | Attached to |
+--------------------------------------+--------------+-----------+------+-------------+
| c24e2a9e-1792-4951-a040-434b87409558 | volume1 | available | 1 | |
+--------------------------------------+--------------+-----------+------+-------------+
查看 Libvirt 虚拟机的 XML 文件内容，disk 标签具有 QoS 属性 <iotune>：
[root@overcloud-compute-0 ~]# virsh dumpxml 1
...
<disk type='block' device='disk'>
<driver name='qemu' type='raw' cache='none' io='native'/>
<source dev='/dev/sdd'/>
<backingStore/>
<target dev='vdb' bus='virtio'/>
<iotune>
<total_iops_sec>200</total_iops_sec>
<total_bytes_sec>2048000</total_bytes_sec>
</iotune>
<serial>c24e2a9e-1792-4951-a040-434b87409558</serial>
<alias name='virtio-disk1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</disk>
通过 virsh 设定 Libvirt 虚拟机的 QoS 属性：
[root@overcloud-compute-0 ~]# virsh blkdeviotune 1 vdb --total_iops_sec 100
[root@overcloud-compute-0 ~]# virsh blkdeviotune 1 vdb --total-bytes-sec 1024000
[root@overcloud-compute-0 ~]# virsh dumpxml 1
...
<disk type='block' device='disk'>
<driver name='qemu' type='raw' cache='none' io='native'/>
<source dev='/dev/sdd'/>
<backingStore/>
<target dev='vdb' bus='virtio'/>
<iotune>
<total_bytes_sec>1024000</total_bytes_sec>
<total_iops_sec>100</total_iops_sec>
</iotune>
<serial>c24e2a9e-1792-4951-a040-434b87409558</serial>
<alias name='virtio-disk1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</disk>
NOTE：Qos 一般来说都是在一个建议值上下浮动的，所以可以通过指定 --total-iops-sec-max 来固定上限。
参考文章
Capacity based quality of service
https://blog.csdn.net/LL_JCB/article/details/80412362