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Adds info about CPU, disk, vif, bandwidth quotas on flavors.
Fix bug 1090654 Fix bug 1210248 Change-Id: I63b962dc6c9caf23b412782f00e1fe5623be68f5
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| <?xml version="1.0" encoding="UTF-8"?> | ||
| <section xml:id="customize-flavors" | ||
| xmlns="http://docbook.org/ns/docbook" | ||
| xmlns:xi="http://www.w3.org/2001/XInclude" | ||
| xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"> | ||
| <title>Customizing Flavors</title> | ||
| <para>The <command>nova flavor-create</command> command allows | ||
| authorized users to create new flavors. Additional flavor | ||
| manipulation commands can be shown with the command | ||
| <command>nova help | grep flavor</command>. Note that the | ||
| OpenStack Dashboard simulates the ability to modify an | ||
| existing flavor by deleting an existing flavor and creating a | ||
| new one with the same name.</para> | ||
| <para>Flavors define a number of elements:</para> | ||
| <itemizedlist> | ||
| <listitem> | ||
| <para><literal>ID</literal>: a unique numeric id</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para><literal>Name</literal>: a descriptive name. | ||
| <replaceable>xx</replaceable>.<replaceable>size_name</replaceable> | ||
| is typically not required, though some third party | ||
| tools may rely on it.</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para><literal>Memory_MB</literal>: virtual machine memory | ||
| in megabytes</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para><literal>Disk</literal>: virtual root disk size in | ||
| gigabytes. This is an ephemeral disk that the base | ||
| image is copied into. When booting from a persistent | ||
| volume it is not used. The "0" size is a special case | ||
| which uses the native base image size as the size of | ||
| the ephemeral root volume.</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para><literal>Ephemeral</literal>: specifies the size of | ||
| a secondary ephemeral data disk. This is an empty, | ||
| unformatted disk and exists only for the life of the | ||
| instance.</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para><literal>Swap</literal>: optional swap space | ||
| allocation for the instance</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para><literal>VCPUs</literal>: number of virtual CPUs | ||
| presented to the instance</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para><literal>RXTX_Factor</literal>: 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).</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para><literal>Is_Public</literal>: Boolean value, whether | ||
| flavor is available to all users or private to the | ||
| tenant it was created in. Defaults to True.</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para><literal>extra_specs</literal>: additional optional | ||
| restrictions on which compute nodes the flavor can run | ||
| on. This is implemented as key/value pairs that must | ||
| match against the corresponding key/value pairs on | ||
| compute nodes. Can be used to implement things like | ||
| special resources (e.g., flavors that can only run on | ||
| compute nodes with GPU hardware).</para> | ||
| </listitem> | ||
| </itemizedlist> | ||
| <para>Flavor customization can be limited by the hypervisor in | ||
| use, for example the libvirt driver enables quotas on CPUs | ||
| available to a VM, disk tuning, bandwidth I/O, and instance | ||
| VIF traffic control.</para> | ||
| <para>You can configure the CPU limits with three control | ||
| parameters with the nova-manage tool. Here is an example of | ||
| configuring the I/O limit:</para> | ||
| <screen><prompt>#</prompt> <userinput>nova-manage flavor set_key --name m1.small --key quota:read_bytes_sec --value 10240000</userinput></screen> | ||
| <screen><prompt>#</prompt> <userinput>nova-manage flavor set_key --name m1.small --key quota:read_bytes_sec --value 10240000</userinput></screen> | ||
| <para>There are CPU control parameters for weight shares, | ||
| enforcement intervals for runtime quotas, and a quota for | ||
| maximum allowed bandwidth.</para> | ||
| <para>The optional cpu_shares element specifies the proportional | ||
| weighted share for the domain. If this element is omitted, the | ||
| service defaults to the OS provided defaults. There is no unit | ||
| for the value, it's a relative measure based on the setting of | ||
| other VMs. For example, a VM configured with value 2048 will | ||
| get twice as much CPU time as a VM configured with value 1024.</para> | ||
| <para>The optional cpu_period element specifies the enforcement | ||
| interval(unit: microseconds) for QEMU and LXC hypervisors. | ||
| Within period, each VCPU of the domain will not be allowed to | ||
| consume more than quota worth of runtime. The value should be | ||
| in range [1000, 1000000]. A period with value 0 means no | ||
| value.</para> | ||
| <para>The optional cpu_quota element specifies the maximum allowed | ||
| bandwidth(unit: microseconds). A domain with quota as any | ||
| negative value 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. An | ||
| example:</para> | ||
| <screen> | ||
| <prompt>#</prompt> <userinput>nova flavor-key m1.low_cpu set cpu_quota=10000</userinput></screen> | ||
| <screen> | ||
| <prompt>#</prompt> <userinput>nova flavor-key m1.low_cpu set cpu_period=20000</userinput></screen> | ||
| <para>In that example, the instance of m1.low_cpu can only consume | ||
| a maximum of 50% CPU of a physical CPU computing | ||
| capability.</para> | ||
| <para>Through quotas for disk I/O, you can set maximum disk write | ||
| to 10MB/sec for VM user for example:</para> | ||
| <screen><prompt>#</prompt> <userinput>nova flavor-set m1.medium set disk_write_bytes_sec=10240000</userinput></screen> | ||
| <para>These are the options for disk I/O:</para> | ||
| <itemizedlist> | ||
| <listitem> | ||
| <para>disk_read_bytes_sec</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>disk_read_iops_sec</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>disk_write_bytes_sec</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>disk_write_iops_sec</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>disk_total_bytes_sec</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>disk_total_iops_sec</para> | ||
| </listitem> | ||
| </itemizedlist> | ||
| <para>These are the options for vif I/O:</para> | ||
| <para> | ||
| <itemizedlist> | ||
| <listitem> | ||
| <para>vif_inbound_ average</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>vif_inbound_burst</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>vif_inbound_peak</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>vif_outbound_ average</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>vif_outbound_burst</para> | ||
| </listitem> | ||
| <listitem> | ||
| <para>vif_outbound_peak</para> | ||
| </listitem> | ||
| </itemizedlist> | ||
| </para> | ||
| <para>Incoming and outgoing traffic can be shaped independently. | ||
| The bandwidth element can have at most one inbound and at most | ||
| one outbound child element. Leaving any of these children | ||
| element out result in no QoS applied on that traffic | ||
| direction. So, when you want to shape only the network's | ||
| incoming traffic, use inbound only, and vice versa. Each of | ||
| these elements have one mandatory attribute average. It | ||
| specifies average bit rate on the interface being shaped. Then | ||
| there are two optional attributes: peak, which specifies | ||
| maximum rate at which bridge can send data, and burst, amount | ||
| of bytes that can be burst at peak speed. Accepted values for | ||
| attributes are integer numbers, The units for average and peak | ||
| attributes are kilobytes per second, and for the burst just | ||
| kilobytes. The rate is shared equally within domains connected | ||
| to the network.</para> | ||
| <para>Here are some examples for configuring a bandwidth limit for | ||
| instance network traffic:</para> | ||
| <screen><prompt>#</prompt> <userinput>nova-manage flavor set_key --name m1.small --key quota:inbound_average --value 10240</userinput> | ||
| </screen> | ||
| <screen><prompt>#</prompt><userinput>nova-manage flavor set_key --name m1.small --key quota:outbound_average --value 10240</userinput></screen> | ||
| </section> |
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