openstack-manuals/doc/common/section_cli_nova_customize_flavors.xml
Andreas Jaeger b0ce83d945 Use common entities file
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common/entities/openstack.ent.

Change-Id: I99f905be679eab34059a30311f11189c17b5498c
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE section[
<!ENTITY % openstack SYSTEM "entities/openstack.ent">
%openstack;
]>
<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>Admin users can use the <command>nova flavor-</command> commands to customize and manage
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.</computeroutput></screen>
<note>
<itemizedlist>
<listitem><para>Configuration rights can be delegated to additional users
by redefining the access controls for <option>compute_extension:flavormanage</option>
in <filename>/etc/nova/policy.json</filename> on the
<systemitem class="server">nova-api</systemitem> server.</para></listitem>
<listitem><para>To modify an existing flavor in the dashboard, you must
delete the flavor and create a modified one with the same
name.</para></listitem>
</itemizedlist>
</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><para>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.</para></td>
</tr>
</tbody>
</table>
<para>Flavor customization can be limited by the hypervisor in use. For example the
<systemitem>libvirt</systemitem> driver enables quotas on CPUs available to a VM, disk
tuning, bandwidth I/O, watchdog behavior, random number generator device control, and
instance VIF traffic control.</para>
<variablelist>
<varlistentry><term>CPU limits</term>
<listitem><para>You can configure the CPU limits with control parameters with the <command>nova</command>
client. For example, to configure the I/O limit, use:</para>
<screen><prompt>$</prompt> <userinput>nova flavor-key m1.small set quota:read_bytes_sec=10240000</userinput>
<prompt>$</prompt> <userinput>nova flavor-key m1.small set quota:write_bytes_sec=10240000</userinput></screen>
<para>There are optional CPU control parameters for weight shares, enforcement
intervals for runtime quotas, and a quota for maximum allowed
bandwidth:</para>
<para>
<itemizedlist>
<listitem>
<para><literal>cpu_shares</literal> specifies the proportional
weighted share for the domain. If this element is omitted, the
service defaults to the OS provided defaults. There is no unit
for the value; it is a relative measure based on the setting of
other VMs. For example, a VM configured with value 2048 gets
twice as much CPU time as a VM configured with value
1024.</para>
</listitem>
<listitem>
<para><literal>cpu_period</literal> specifies the enforcement
interval (unit: microseconds) for QEMU and LXC hypervisors.
Within a period, each VCPU of the domain is not allowed to
consume more than the quota worth of runtime. The value should
be in range <literal>[1000, 1000000]</literal>. A period with
value 0 means no value.</para>
</listitem>
<listitem>
<para><literal>cpu_quota</literal> specifies the maximum allowed
bandwidth (unit: microseconds). A domain with a negative-value quota
indicates that the domain has infinite bandwidth, which means that
it is not bandwidth controlled. The value should be in range
<literal>[1000, 18446744073709551]</literal> or less than 0. A
quota with value 0 means no value. You can use this feature to
ensure that all vCPUs run at the same speed. For example:</para>
<screen><prompt>$</prompt> <userinput>nova flavor-key m1.low_cpu set quota:cpu_quota=10000</userinput>
<prompt>$</prompt> <userinput>nova flavor-key m1.low_cpu set quota:cpu_period=20000</userinput></screen>
<para>In this example, the instance of
<literal>m1.low_cpu</literal> can only consume a maximum
of 50% CPU of a physical CPU computing capability.</para>
</listitem>
</itemizedlist>
</para>
</listitem>
</varlistentry>
<varlistentry><term>Disk tuning</term>
<listitem><para>Using disk I/O quotas, you can set maximum disk write to 10 MB per second for a VM user. For
example:</para>
<screen><prompt>$</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></listitem>
</varlistentry>
<varlistentry><term>Bandwidth I/O</term>
<listitem><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. If you leave any of
these children element 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.</para>
<para>There are also two optional attributes (integer): <option>peak</option>, which
specifies maximum rate at which bridge can send data (kilobytes/second), and
<option>burst</option>, the amount of bytes that can be burst at peak speed
(kilobytes). The rate is shared equally within domains connected to the
network.</para>
<para>The following 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></listitem>
</varlistentry>
<varlistentry><term>Watchdog behavior</term>
<listitem><para>For the <systemitem>libvirt</systemitem> driver, you can enable and set the behavior of a
virtual hardware watchdog device for each flavor. Watchdog devices keep an eye
on the guest server, and carry out the configured action if the server hangs.
The watchdog uses the i6300esb device (emulating a PCI Intel 6300ESB). If
<literal>hw_watchdog_action</literal> is not specified, the watchdog is
disabled.</para>
<para>To set the behavior, use:</para>
<screen><prompt>$</prompt> <userinput>nova flavor-key <replaceable>FLAVOR-NAME</replaceable> set hw_watchdog_action=<replaceable>ACTION</replaceable></userinput></screen>
<para>Valid <replaceable>ACTION</replaceable> values are:</para>
<itemizedlist>
<listitem>
<para><literal>disabled</literal>&mdash;(default) The device is not
attached.</para></listitem>
<listitem>
<para><literal>reset</literal>&mdash;Forcefully reset the guest.
</para>
</listitem>
<listitem>
<para><literal>poweroff</literal>&mdash;Forcefully power off the
guest.</para>
</listitem>
<listitem>
<para><literal>pause</literal>&mdash;Pause the guest.</para>
</listitem>
<listitem>
<para><literal>none</literal>&mdash;Only enable the watchdog; do
nothing if the server hangs.</para>
</listitem>
</itemizedlist>
<note><para>Watchdog behavior set using a specific image's properties will override behavior set using
flavors.</para></note>
</listitem>
</varlistentry>
<varlistentry>
<term>Random-number generator</term>
<listitem><para>If a random-number generator device has been added to the instance through its image
properties, the device can be enabled and configured using:</para>
<screen><prompt>$</prompt> <userinput>nova flavor-key <replaceable>FLAVOR-NAME</replaceable> set hw_rng:allowed=True</userinput>
<prompt>$</prompt> <userinput>nova flavor-key <replaceable>FLAVOR-NAME</replaceable> set hw_rng:rate_bytes=<replaceable>RATE-BYTES</replaceable></userinput>
<prompt>$</prompt> <userinput>nova flavor-key <replaceable>FLAVOR-NAME</replaceable> set hw_rng:rate_period=<replaceable>RATE-PERIOD</replaceable></userinput></screen>
<para>Where:</para>
<itemizedlist>
<listitem>
<para><replaceable>RATE-BYTES</replaceable>&mdash;(Integer) Allowed amount of
bytes that the guest can read from the host's entropy per period.</para>
</listitem>
<listitem>
<para><replaceable>RATE-PERIOD</replaceable>&mdash;(Integer) Duration of the
read period in seconds.</para>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
<varlistentry><term>Instance VIF traffic control</term>
<listitem><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></listitem>
</varlistentry>
</variablelist>
</section>