openstack-manuals/doc/common/section_cli_nova_customize_flavors.xml
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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>Flavors</title>
<para>Authorized users can use the <command>nova
flavor-create</command> command to create flavors. To see
the available flavor-related commands, run:</para>
<screen><prompt>$</prompt> <userinput>nova help | grep flavor</userinput>
<computeroutput>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.
volume-type-delete Delete a specific flavor</computeroutput></screen>
<note>
<para>To modify an existing flavor in the dashboard, you must
delete the flavor and create a modified one with the same
name.</para>
</note>
<para>Flavors define these elements:</para>
<table rules="all" width="75%">
<caption>Identity Service configuration file
sections</caption>
<col width="15%"/>
<col width="85%"/>
<thead>
<tr>
<td>Element</td>
<td>Description</td>
</tr>
</thead>
<tbody>
<tr>
<td><literal>Name</literal></td>
<td>A descriptive name.
<replaceable>xx</replaceable>.<replaceable>size_name</replaceable>
is typically not required, though some third party
tools may rely on it.</td>
</tr>
<tr>
<td><literal>Memory_MB</literal></td>
<td>Virtual machine memory in megabytes.</td>
</tr>
<tr>
<td><literal>Disk</literal></td>
<td>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.</td>
</tr>
<tr>
<td><literal>Ephemeral</literal></td>
<td>Specifies the size of a secondary ephemeral data
disk. This is an empty, unformatted disk and
exists only for the life of the instance.</td>
</tr>
<tr>
<td><literal>Swap</literal></td>
<td>Optional swap space allocation for the
instance.</td>
</tr>
<tr>
<td><literal>VCPUs</literal></td>
<td>Number of virtual CPUs presented to the
instance.</td>
</tr>
<tr>
<td><literal>RXTX_Factor</literal></td>
<td>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.</td>
</tr>
<tr>
<td><literal>Is_Public</literal></td>
<td>Boolean value, whether flavor is available to all
users or private to the tenant it was created in.
Defaults to True.</td>
</tr>
<tr>
<td><literal>extra_specs</literal></td>
<td>Key and value pairs that define on which compute
nodes a flavor can run. These pairs must match
corresponding pairs on the compute nodes. Use to
implement special resources, such as flavors that
run on only compute nodes with GPU hardware.</td>
</tr>
</tbody>
</table>
<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 control parameters
with the nova tool. For example, to configure the I/O
limit:</para>
<screen><prompt>#</prompt> <userinput>nova flavor-key m1.small set quota:read_bytes_sec=10240000</userinput>
<prompt>#</prompt> <userinput>nova flavor-key m1.small set quota:write_bytes_sec=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 <literal>cpu_shares</literal> 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 is a relative
measure based on the setting of other VMs. For example, a VM
configured with value 2048 gets twice as much CPU time as a VM
configured with value 1024.</para>
<para>The optional <literal>cpu_period</literal> element specifies
the enforcement interval (unit: microseconds) for QEMU and LXC
hypervisors. Within a period, each VCPU of the domain is not
allowed to consume more than the quota worth of runtime. The
value should be in range <literal>[1000, 1000000]</literal>. A
period with value 0 means no value.</para>
<para>The optional <literal>cpu_quota</literal> element specifies
the maximum allowed bandwidth (unit: microseconds). A domain
with a quota with a negative value indicates that the domain
has infinite bandwidth, which means that it is not bandwidth
controlled. The value should be in range <literal>[1000,
18446744073709551]</literal> 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:</para>
<screen><prompt>#</prompt> <userinput>nova flavor-key m1.low_cpu set quota:cpu_quota=10000</userinput>
<prompt>#</prompt> <userinput>nova flavor-key m1.low_cpu set quota:cpu_period=20000</userinput></screen>
<para>In this example, the instance of
<literal>m1.low_cpu</literal> can only consume a maximum
of 50% CPU of a physical CPU computing capability.</para>
<para>Through disk I/O quotas, you can set maximum disk write to
10 MB per second for a VM user. For example:</para>
<screen><prompt>#</prompt> <userinput>nova flavor-key m1.medium set disk_write_bytes_sec=10485760</userinput></screen>
<para>The disk I/O options are:</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>The vif I/O options are:</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>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 quality of service (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.</para>
<para>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>This example configures a bandwidth limit for instance
network traffic:</para>
<screen><prompt>#</prompt> <userinput>nova flavor-key m1.small set quota:inbound_average=10240</userinput>
<prompt>#</prompt> <userinput>nova flavor-key m1.small set quota:outbound_average=10240</userinput></screen>
<para>Flavors can also be assigned to particular projects. By
default, a flavor is public and available to all projects.
Private flavors are only accessible to those on the access
list and are invisible to other projects. To create and assign
a private flavor to a project, run these commands:</para>
<screen><prompt>#</prompt> <userinput>nova flavor-create --is-public false p1.medium auto 512 40 4</userinput>
<prompt>#</prompt> <userinput>nova flavor-access-add 259d06a0-ba6d-4e60-b42d-ab3144411d58 86f94150ed744e08be565c2ff608eef9</userinput></screen>
</section>