nova Flavors

$ nova help | grep flavor-
  flavor-access-add     Add flavor access for the given tenant.
  flavor-access-list    Print access information about the given flavor.
  flavor-access-remove  Remove flavor access for the given tenant.
  flavor-create         Create a new flavor
  flavor-delete         Delete a specific flavor
  flavor-key            Set or unset extra_spec for a flavor.
  flavor-list           Print a list of available 'flavors' (sizes of
  flavor-show           Show details about the given flavor.

Flavors define these elements:

Element	Description
Name	一般不需要，直接使用flavor ID.
Memory_MB	虚拟机内存
Disk	vm的root磁盘，base image会被copy到这上面。当从一个 persistent volume启动时这个参数不被用到。
Ephemeral	vm的第二个磁盘，随vm的消失而消失。没有被格式化
Swap	Optional swap space allocation for the instance.
VCPUs	Number of virtual CPUs presented to the instance.
RXTX_Factor	Optional property allows created servers to have a different bandwidth cap than that defined in the network they are attached to. This factor is multiplied by the rxtx_base property of the network. Default value is 1.0. That is, the same as attached network. This parameter is only available for Xen or NSX based systems.
Is_Public	Boolean value, whether flavor is available to all users or private to the tenant it was created in. Defaults to True.
extra_specs	k/v键值，定义flavor可以运行在那些计算节点上。键值必须与计算节点上的键值匹配，用来实现某些特殊的资源，比如定义flavor只可以运行在有GPU硬件的node上。

Flavor customization

CPU limits

• cpu_shares. CPU相对权重，如VM的cpu权重为2048的要比1024得到2倍的CPU时间，如果不设置，则又主机默认设置。

• cpu_shares_level. 用在 VMWare上, 与cpu_shares作用相似. 可以为custom, high,normal, or low. 如果是 custom, 需要设置cpu_shares_share来决定cpu权重.

• cpu_period. Specifies the enforcement interval (unit: microseconds) for QEMU and LXC hypervisors. 在一个period周期, 该VM的每个VCPU运行时间不能超过 quota. 设置值的范围为[1000, 1000000]. A period with value 0 means no value.

• cpu_limit. Specifies the upper limit for VMware machine CPU allocation in MHz. This parameter ensures that a machine never uses more than the defined amount of CPU time. It can be used to enforce a limit on the machine’s CPU performance.

• cpu_reservation. Specifies the guaranteed minimum CPU reservation in MHz for VMware. This means that if needed, the machine will definitely get allocated the reserved amount of CPU cycles.

• cpu_quota. Specifies the maximum allowed bandwidth (unit: microseconds). A domain with a negative-value quota indicates that the domain has infinite bandwidth, which means that it is not bandwidth controlled. The value should be in range [1000,18446744073709551] or less than 0. A quota with value 0 means no value. You can use this feature to ensure that all vCPUs run at the same speed. For example:

$ nova flavor-key m1.low_cpu set quota:cpu_quota=10000
$ nova flavor-key m1.low_cpu set quota:cpu_period=20000

Memory limits

For VMware, you can configure the memory limits with control parameters.

Use these optional parameters to limit the memory allocation, guarantee minimum memory reservation, and to specify shares used in case of resource contention:

• memory_limit: 虚拟机最大内存.

• memory_reservation:  VMware上虚拟机最少/保证有的内存

• memory_shares_level: On VMware, specifies the allocation level. This can be custom,high, normal or low. If you choose custom, set the number of shares usingmemory_shares_share.

• memory_shares_share: 

  $ nova flavor-key m1.medium set quota:memory_shares_level=custom
  $ nova flavor-key m1.medium set quota:memory_shares_share=15

Disk I/O limits

用在VMware上，与cpu/内存设置类似。For VMware, you can configure the resource limits for disk with control parameters.

Use these optional parameters to limit the disk utilization, guarantee disk allocation, and to specify shares used in case of resource contention. This allows the VMWare driver to enable disk allocations for the running instance.

• disk_io_limit: Specifies the upper limit for disk utilization in I/O per second. The utilization of a virtual machine will not exceed this limit, even if there are available resources. The default value is -1 which indicates unlimited usage.

• disk_io_reservation: Specifies the guaranteed minimum disk allocation in terms of IOPS.

• disk_io_shares_level: Specifies the allocation level. This can be custom, high,normal or low. If you choose custom, set the number of shares usingdisk_io_shares_share.

• disk_io_shares_share: Specifies the number of shares allocated in the event thatcustom is used. When there is resource contention, this value is used to determine the resource allocation.

  The example below sets the disk_io_reservation to 2000 IOPS.

  $ nova flavor-key m1.medium set quota:disk_io_reservation=2000
  

Disk tuning

Using disk I/O quotas, you can set maximum disk write to 10 MB per second for a VM user. For example:

$ nova flavor-key m1.medium set quota:disk_write_bytes_sec=10485760

The disk I/O options are:

• disk_read_bytes_sec
• disk_read_iops_sec
• disk_write_bytes_sec
• disk_write_iops_sec
• disk_total_bytes_sec
• disk_total_iops_sec

Bandwidth I/O

The vif I/O options are:

• vif_inbound_ average
• vif_inbound_burst
• vif_inbound_peak
• vif_outbound_ average
• vif_outbound_burst
• vif_outbound_peak

Incoming and outgoing traffic can be shaped independently. The bandwidth element can have at most, one inbound and at most, one outbound child element. If you leave any of these child elements out, no quality of service (QoS) is applied on that traffic direction. So, if you want to shape only the network’s incoming traffic, use inbound only (and vice versa). Each element has one mandatory attribute average, which specifies the average bit rate on the interface being shaped.

There are also two optional attributes (integer): peak, which specifies the maximum rate at which a bridge can send data (kilobytes/second), and burst, the amount of bytes that can be burst at peak speed (kilobytes). The rate is shared equally within domains connected to the network.

The example below sets network traffic bandwidth limits for existing flavor as follows:

• Outbound traffic:
  • average: 256 Mbps (32768 kilobytes/second)
  • peak: 512 Mbps (65536 kilobytes/second)
  • burst: 65536 kilobytes
• Inbound traffic:
  • average: 256 Mbps (32768 kilobytes/second)
  • peak: 512 Mbps (65536 kilobytes/second)
  • burst: 65536 kilobytes

$ nova flavor-key nlimit set quota:vif_outbound_average=32768
$ nova flavor-key nlimit set quota:vif_outbound_peak=65536
$ nova flavor-key nlimit set quota:vif_outbound_burst=65536
$ nova flavor-key nlimit set quota:vif_inbound_average=32768
$ nova flavor-key nlimit set quota:vif_inbound_peak=65536
$ nova flavor-key nlimit set quota:vif_inbound_burst=65536

 Note

All the speed limit values in above example are specified in kilobytes/second. And burst values are in kilobytes.

Random-number generator

如果一个random-number generator device 通过image properties添加到vm, 可以在flavor来enable和设置（如果没有对应的device？）:

$ nova flavor-key FLAVOR-NAME set hw_rng:allowed=True
$ nova flavor-key FLAVOR-NAME set hw_rng:rate_bytes=RATE-BYTES
$ nova flavor-key FLAVOR-NAME set hw_rng:rate_period=RATE-PERIOD

Where:

• RATE-BYTES—(Integer) 每个周期可以从host的entropy 读取多少字节.
• RATE-PERIOD—(Integer) 每个周期多少秒.

Watchdog behavior

如果VM server hangs. The watchdog uses the i6300esb device (emulating a PCI Intel 6300ESB). If hw:watchdog_action is not specified, the watchdog is disabled.

To set the behavior, use:

$ nova flavor-key FLAVOR-NAME set hw:watchdog_action=ACTION

Valid ACTION values are:

• disabled—(default) The device is not attached.
• reset—Forcefully reset the guest.
• poweroff—Forcefully power off the guest.
• pause—Pause the guest.
• none—Only enable the watchdog; do nothing if the server hangs.

Note

image’s watchdog 设置会覆盖flavors的设置.

CPU toplogy

设置vm的cpu toplogy。 max limit类型的设置也可以通过image 属性来设置.

$ nova flavor-key FLAVOR-NAME set hw:cpu_sockets=FLAVOR-SOCKETS
$ nova flavor-key FLAVOR-NAME set hw:cpu_cores=FLAVOR-CORES
$ nova flavor-key FLAVOR-NAME set hw:cpu_threads=FLAVOR-THREADS
$ nova flavor-key FLAVOR-NAME set hw:cpu_max_sockets=FLAVOR-SOCKETS
$ nova flavor-key FLAVOR-NAME set hw:cpu_max_cores=FLAVOR-CORES
$ nova flavor-key FLAVOR-NAME set hw:cpu_max_threads=FLAVOR-THREADS

Where:

• FLAVOR-SOCKETS—(Integer) The number of sockets for the guest VM. By this is set to the number of vCPUs requested.
• FLAVOR-CORES—(Integer) The number of cores per socket for the guest VM. By this is set to 1.
• FLAVOR-THREADS—(Integer) The number of threads per core for the guest VM. By this is set to 1.

Project private flavors

默认是public，所有租户都可用。

$ nova flavor-create --is-public false p1.medium auto 512 40 4
$ nova flavor-access-add 259d06a0-ba6d-4e60-b42d-ab3144411d58 86f94150ed744e08be565c2ff608eef9

http://docs.openstack.org/admin-guide-cloud/compute-flavors.html