416 lines
21 KiB
XML
416 lines
21 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE section[
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<!ENTITY % openstack SYSTEM "entities/openstack.ent">
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%openstack;
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]>
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<section xmlns="http://docbook.org/ns/docbook"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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version="5.0"
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xml:id="customize-flavors">
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<title>Flavors</title>
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<para>Admin users can use the <command>nova flavor-</command>
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commands to customize and manage flavors. To see the available
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flavor-related commands, run:</para>
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<screen><prompt>$</prompt> <userinput>nova help | grep flavor-</userinput>
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<computeroutput> flavor-access-add Add flavor access for the given tenant.
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flavor-access-list Print access information about the given flavor.
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flavor-access-remove
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Remove flavor access for the given tenant.
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flavor-create Create a new flavor
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flavor-delete Delete a specific flavor
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flavor-key Set or unset extra_spec for a flavor.
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flavor-list Print a list of available 'flavors' (sizes of
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flavor-show Show details about the given flavor.</computeroutput></screen>
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<note>
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<itemizedlist>
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<listitem>
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<para>Configuration rights can be delegated to
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additional users by redefining the access controls
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for
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<option>compute_extension:flavormanage</option>
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in <filename>/etc/nova/policy.json</filename> on
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the <systemitem class="server"
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>nova-api</systemitem> server.</para>
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</listitem>
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<listitem>
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<para>To modify an existing flavor in the dashboard,
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you must delete the flavor and create a modified
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one with the same name.</para>
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</listitem>
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</itemizedlist>
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</note>
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<para>Flavors define these elements:</para>
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<table rules="all" width="75%">
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<caption>Identity Service configuration file
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sections</caption>
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<col width="15%"/>
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<col width="85%"/>
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<thead>
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<tr>
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<td>Element</td>
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<td>Description</td>
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</tr>
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</thead>
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<tbody>
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<tr>
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<td><literal>Name</literal></td>
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<td>A descriptive name.
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<replaceable>XX</replaceable>.<replaceable>SIZE_NAME</replaceable>
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is typically not required, though some third party
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tools may rely on it.</td>
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</tr>
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<tr>
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<td><literal>Memory_MB</literal></td>
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<td>Virtual machine memory in megabytes.</td>
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</tr>
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<tr>
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<td><literal>Disk</literal></td>
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<td>Virtual root disk size in gigabytes. This is an
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ephemeral disk that the base image is copied into.
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When booting from a persistent volume it is not
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used. The "0" size is a special case which uses
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the native base image size as the size of the
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ephemeral root volume.</td>
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</tr>
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<tr>
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<td><literal>Ephemeral</literal></td>
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<td>Specifies the size of a secondary ephemeral data
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disk. This is an empty, unformatted disk and
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exists only for the life of the instance.</td>
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</tr>
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<tr>
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<td><literal>Swap</literal></td>
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<td>Optional swap space allocation for the
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instance.</td>
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</tr>
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<tr>
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<td><literal>VCPUs</literal></td>
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<td>Number of virtual CPUs presented to the
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instance.</td>
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</tr>
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<tr>
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<td><literal>RXTX_Factor</literal></td>
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<td>Optional property allows created servers to have a different bandwidth cap than
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that defined in the network they are attached to. This factor is multiplied by
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the rxtx_base property of the network. Default value is 1.0. That is, the same
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as attached network. This parameter is only available for Xen or NSX based
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systems.</td>
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</tr>
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<tr>
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<td><literal>Is_Public</literal></td>
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<td>Boolean value, whether flavor is available to all
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users or private to the tenant it was created in.
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Defaults to True.</td>
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</tr>
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<tr>
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<td><literal>extra_specs</literal></td>
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<td><para>Key and value pairs that define on which
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compute nodes a flavor can run. These pairs
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must match corresponding pairs on the compute
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nodes. Use to implement special resources,
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such as flavors that run on only compute nodes
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with GPU hardware.</para></td>
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</tr>
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</tbody>
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</table>
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<para>Flavor customization can be limited by the hypervisor in
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use. For example the <systemitem>libvirt</systemitem> driver
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enables quotas on CPUs available to a VM, disk tuning,
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bandwidth I/O, watchdog behavior, random number generator
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device control, and instance VIF traffic control.</para>
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<variablelist>
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<varlistentry>
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<term>CPU limits</term>
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<listitem>
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<para>You can configure the CPU limits with control
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parameters with the <command>nova</command>
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client. For example, to configure the I/O limit,
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use:</para>
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<screen><prompt>$</prompt> <userinput>nova flavor-key m1.small set quota:read_bytes_sec=10240000</userinput>
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<prompt>$</prompt> <userinput>nova flavor-key m1.small set quota:write_bytes_sec=10240000</userinput></screen>
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<para>Use these optional parameters to control weight
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shares, enforcement intervals for runtime quotas,
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and a quota for maximum allowed bandwidth:</para>
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<itemizedlist>
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<listitem>
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<para><option>cpu_shares</option>. Specifies the proportional weighted share
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for the domain. If this element is
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omitted, the service defaults to the OS
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provided defaults. There is no unit for
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the value; it is a relative measure based
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on the setting of other VMs. For example,
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a VM configured with value 2048 gets twice
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as much CPU time as a VM configured with
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value 1024.</para>
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</listitem>
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<listitem>
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<para><option>cpu_period</option>. Specifies the enforcement interval (unit:
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microseconds) for QEMU and LXC
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hypervisors. Within a period, each VCPU of
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the domain is not allowed to consume more
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than the quota worth of runtime. The value
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should be in range <literal>[1000,
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1000000]</literal>. A period with
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value 0 means no value.</para>
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</listitem>
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<listitem>
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<para><option>cpu_limit</option>. Specifies the upper limit for VMware machine CPU allocation in MHz.
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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.
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</para>
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</listitem>
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<listitem>
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<para><option>cpu_reservation</option>. Specifies the guaranteed minimum CPU reservation in MHz for VMware.
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This means that if needed, the machine will definitely get allocated the reserved amount of CPU cycles.
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</para>
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</listitem>
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<listitem>
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<para><option>cpu_quota</option>. Specifies the maximum allowed bandwidth
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(unit: microseconds). A domain with a
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negative-value quota indicates that the
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domain has infinite bandwidth, which means
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that it is not bandwidth controlled. The
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value should be in range <literal>[1000,
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18446744073709551]</literal> or less
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than 0. A quota with value 0 means no
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value. You can use this feature to ensure
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that all vCPUs run at the same speed. For
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example:</para>
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<screen><prompt>$</prompt> <userinput>nova flavor-key m1.low_cpu set quota:cpu_quota=10000</userinput>
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<prompt>$</prompt> <userinput>nova flavor-key m1.low_cpu set quota:cpu_period=20000</userinput></screen>
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<para>In this example, the instance of
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<literal>m1.low_cpu</literal> can only
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consume a maximum of 50% CPU of a physical
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CPU computing capability.</para>
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</listitem>
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</itemizedlist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Disk tuning</term>
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<listitem>
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<para>Using disk I/O quotas, you can set maximum disk
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write to 10 MB per second for a VM user. For
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example:</para>
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<screen><prompt>$</prompt> <userinput>nova flavor-key m1.medium set quota:disk_write_bytes_sec=10485760</userinput></screen>
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<para>The disk I/O options are:</para>
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<itemizedlist>
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<listitem>
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<para>disk_read_bytes_sec</para>
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</listitem>
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<listitem>
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<para>disk_read_iops_sec</para>
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</listitem>
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<listitem>
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<para>disk_write_bytes_sec</para>
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</listitem>
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<listitem>
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<para>disk_write_iops_sec</para>
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</listitem>
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<listitem>
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<para>disk_total_bytes_sec</para>
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</listitem>
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<listitem>
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<para>disk_total_iops_sec</para>
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</listitem>
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</itemizedlist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Bandwidth I/O</term>
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<listitem>
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<para>The vif I/O options are:</para>
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<itemizedlist>
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<listitem>
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<para>vif_inbound_ average</para>
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</listitem>
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<listitem>
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<para>vif_inbound_burst</para>
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</listitem>
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<listitem>
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<para>vif_inbound_peak</para>
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</listitem>
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<listitem>
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<para>vif_outbound_ average</para>
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</listitem>
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<listitem>
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<para>vif_outbound_burst</para>
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</listitem>
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<listitem>
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<para>vif_outbound_peak</para>
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</listitem>
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</itemizedlist>
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<para>Incoming and outgoing traffic can be shaped
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independently. The bandwidth element can have at
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most, one inbound and at most, one outbound child
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element. If you leave any of these child elements
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out, no quality of service (QoS) is applied on
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that traffic direction. So, if you want to shape
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only the network's incoming traffic, use inbound
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only (and vice versa). Each element has one
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mandatory attribute average, which specifies the
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average bit rate on the interface being
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shaped.</para>
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<para>There are also two optional attributes
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(integer): <option>peak</option>, which specifies
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the maximum rate at which a bridge can send data
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(kilobytes/second), and <option>burst</option>,
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the amount of bytes that can be burst at peak
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speed (kilobytes). The rate is shared equally
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within domains connected to the network.</para>
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<para>Below example sets network traffic bandwidth limits for
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existing flavor as follow:
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</para>
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<itemizedlist>
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<listitem>
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<para>Outbound traffic:
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<itemizedlist>
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<listitem>
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<para>
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average: 256 Mbps
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(32768 kilobytes/second)
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</para>
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</listitem>
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<listitem>
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<para>
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peak: 512 Mbps
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(65536 kilobytes/second)
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</para>
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</listitem>
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<listitem>
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<para>
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burst: 100 ms
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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<listitem>
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<para>Inbound traffic:
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<itemizedlist>
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<listitem>
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<para>
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average: 256 Mbps
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(32768 kilobytes/second)
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</para>
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</listitem>
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<listitem>
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<para>
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peak: 512 Mbps
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(65536 kilobytes/second)
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</para>
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</listitem>
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<listitem>
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<para>
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burst: 100 ms
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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</itemizedlist>
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<screen><prompt>$</prompt> <userinput>nova flavor-key nlimit set quota:vif_outbound_average=32768</userinput>
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<prompt>$</prompt> <userinput>nova flavor-key nlimit set quota:vif_outbound_peak=65536</userinput>
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<prompt>$</prompt> <userinput>nova flavor-key nlimit set quota:vif_outbound_burst=6553</userinput>
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<prompt>$</prompt> <userinput>nova flavor-key nlimit set quota:vif_inbound_average=16384</userinput>
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<prompt>$</prompt> <userinput>nova flavor-key nlimit set quota:vif_inbound_peak=32768</userinput>
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<prompt>$</prompt> <userinput>nova flavor-key nlimit set quota:vif_inbound_burst=3276</userinput>
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</screen>
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<note>
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<para>All the speed limit values in above example are
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specified in kilobytes/second. And burst values are in
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kilobytes.</para>
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</note>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Watchdog behavior</term>
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<listitem>
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<para>For the <systemitem>libvirt</systemitem> driver,
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you can enable and set the behavior of a virtual
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hardware watchdog device for each flavor. Watchdog
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devices keep an eye on the guest server, and carry
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out the configured action, if the server hangs.
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The watchdog uses the i6300esb device (emulating a
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PCI Intel 6300ESB). If
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<literal>hw:watchdog_action</literal> is not
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specified, the watchdog is disabled.</para>
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<para>To set the behavior, use:</para>
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<screen><prompt>$</prompt> <userinput>nova flavor-key <replaceable>FLAVOR-NAME</replaceable> set hw:watchdog_action=<replaceable>ACTION</replaceable></userinput></screen>
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<para>Valid <replaceable>ACTION</replaceable> values
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are:</para>
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<itemizedlist>
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<listitem>
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<para><literal>disabled</literal>—(default)
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The device is not attached.</para>
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</listitem>
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<listitem>
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<para><literal>reset</literal>—Forcefully
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reset the guest.</para>
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</listitem>
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<listitem>
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<para><literal>poweroff</literal>—Forcefully
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power off the guest.</para>
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</listitem>
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<listitem>
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<para><literal>pause</literal>—Pause the
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guest.</para>
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</listitem>
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<listitem>
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<para><literal>none</literal>—Only
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enable the watchdog; do nothing if the
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server hangs.</para>
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</listitem>
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</itemizedlist>
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<note>
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<para>Watchdog behavior set using a specific
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image's properties will override behavior set
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using flavors.</para>
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</note>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Random-number generator</term>
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<listitem>
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<para>If a random-number generator device has been
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added to the instance through its image
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properties, the device can be enabled and
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configured using:</para>
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<screen><prompt>$</prompt> <userinput>nova flavor-key <replaceable>FLAVOR-NAME</replaceable> set hw_rng:allowed=True</userinput>
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<prompt>$</prompt> <userinput>nova flavor-key <replaceable>FLAVOR-NAME</replaceable> set hw_rng:rate_bytes=<replaceable>RATE-BYTES</replaceable></userinput>
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<prompt>$</prompt> <userinput>nova flavor-key <replaceable>FLAVOR-NAME</replaceable> set hw_rng:rate_period=<replaceable>RATE-PERIOD</replaceable></userinput></screen>
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<para>Where:</para>
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<itemizedlist>
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<listitem>
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<para><replaceable>RATE-BYTES</replaceable>—(Integer)
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Allowed amount of bytes that the guest can
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read from the host's entropy per
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period.</para>
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</listitem>
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<listitem>
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<para><replaceable>RATE-PERIOD</replaceable>—(Integer)
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Duration of the read period in
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seconds.</para>
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</listitem>
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</itemizedlist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Project private flavors</term>
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<listitem>
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<para>Flavors can also be assigned to particular
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projects. By default, a flavor is public and
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available to all projects. Private flavors are
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only accessible to those on the access list and
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are invisible to other projects. To create and
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assign a private flavor to a project, run these
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commands:</para>
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<screen><prompt>$</prompt> <userinput>nova flavor-create --is-public false p1.medium auto 512 40 4</userinput>
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<prompt>$</prompt> <userinput>nova flavor-access-add 259d06a0-ba6d-4e60-b42d-ab3144411d58 86f94150ed744e08be565c2ff608eef9</userinput></screen>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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