-<listitem>
- <para> </para>
- </listitem>
-</itemizedlist>
- <informaltable frame="none">
- <tgroup cols="1">
- <colspec colname="c1" colwidth="100*"/>
- <tbody>
- <row>
- <entry><para><emphasis role="bold">Note -</emphasis><anchor xml:id="dbdoclet.50438188_pgfId-1292610" xreflabel=""/><emphasis>Using Lustre Failover is optional.</emphasis></para></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- <section remap="h2">
- <title><anchor xml:id="dbdoclet.50438188_pgfId-1292208" xreflabel=""/></title>
- <section remap="h2">
- <title>11.1 <anchor xml:id="dbdoclet.50438188_82389" xreflabel=""/><anchor xml:id="dbdoclet.50438188_60346" xreflabel=""/>Creating a Failover Environment</title>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292209" xreflabel=""/>Lustre provides failover mechanisms only at the file system level. No failover functionality is provided for system-level components, such as node failure detection or power control, as would typically be provided in a complete failover solution. Additional tools are also needed to provide resource fencing, control and monitoring.</para>
- <section remap="h3">
- <title><anchor xml:id="dbdoclet.50438188_pgfId-1292210" xreflabel=""/>11.1.1 Power Management Software</title>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292211" xreflabel=""/>Lustre failover requires power control and management capability to verify that a failed node is shut down before I/O is directed to the failover node. This avoids double-mounting the two nodes, and the risk of unrecoverable data corruption. A variety of power management tools will work, but two packages that are commonly used with Lustre are STONITH and PowerMan.</para>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292212" xreflabel=""/>Shoot The Other Node In The HEAD (STONITH), is a set of power management tools provided with the Linux-HA package. STONITH has native support for many power control devices and is extensible. It uses expect scripts to automate control.</para>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292213" xreflabel=""/>PowerMan, available from the Lawrence Livermore National Laboratory (LLNL), is used to control remote power control (RPC) devices from a central location. PowerMan provides native support for several RPC varieties and expect-like configuration simplifies the addition of new devices.</para>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292214" xreflabel=""/>The latest versions of PowerMan are available at:</para>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292216" xreflabel=""/><link xl:href="http://sourceforge.net/projects/powerman">http://sourceforge.net/projects/powerman</link></para>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292217" xreflabel=""/>For more information about PowerMan, go to:</para>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292219" xreflabel=""/><link xl:href="https://computing.llnl.gov/linux/powerman.html">https://computing.llnl.gov/linux/powerman.html</link></para>
- </section>
- <section remap="h3">
- <title><anchor xml:id="dbdoclet.50438188_pgfId-1292220" xreflabel=""/>11.1.2 Power Equipment</title>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292221" xreflabel=""/>Lustre failover also requires the use of RPC devices, which come in different configurations. Lustre server nodes may be equipped with some kind of service processor that allows remote power control. If a Lustre server node is not equipped with a service processor, then a multi-port, Ethernet-addressable RPC may be used as an alternative. For recommended products, refer to the list of supported RPC devices on the PowerMan website.</para>
- <para><anchor xml:id="dbdoclet.50438188_pgfId-1292223" xreflabel=""/><link xl:href="https://computing.llnl.gov/linux/powerman.html">https://computing.llnl.gov/linux/powerman.html</link></para>
- </section>
+ </itemizedlist>
+ <para>For an overview of failover functionality in a Lustre file system, see <xref
+ xmlns:xlink="http://www.w3.org/1999/xlink" linkend="understandingfailover"/>.</para>
+ <section xml:id="high_availability">
+ <title><indexterm>
+ <primary>High availability</primary>
+ <see>failover</see>
+ </indexterm><indexterm>
+ <primary>failover</primary>
+ </indexterm>Setting Up a Failover Environment</title>
+ <para>The Lustre software provides failover mechanisms only at the layer of the Lustre file
+ system. No failover functionality is provided for system-level components such as failing
+ hardware or applications, or even for the entire failure of a node, as would typically be
+ provided in a complete failover solution. Failover functionality such as node monitoring,
+ failure detection, and resource fencing must be provided by external HA software, such as
+ PowerMan or the open source Corosync and Pacemaker packages provided by Linux operating system
+ vendors. Corosync provides support for detecting failures, and Pacemaker provides the actions
+ to take once a failure has been detected.</para>
+ <section remap="h3">
+ <title><indexterm>
+ <primary>failover</primary>
+ <secondary>power control device</secondary>
+ </indexterm>Selecting Power Equipment</title>
+ <para>Failover in a Lustre file system requires the use of a remote
+ power control (RPC) mechanism, which comes in different configurations.
+ For example, Lustre server nodes may be equipped with IPMI/BMC devices
+ that allow remote power control. In the past, software or even
+ “sneakerware” has been used, but these are not recommended. For
+ recommended devices, refer to the list of supported RPC devices on the
+ website for the PowerMan cluster power management utility:</para>
+ <para><link xmlns:xlink="http://www.w3.org/1999/xlink"
+ xlink:href="https://linux.die.net/man/7/powerman-devices">
+ https://linux.die.net/man/7/powerman-devices</link></para>
+ </section>
+ <section remap="h3">
+ <title><indexterm>
+ <primary>failover</primary>
+ <secondary>power management software</secondary>
+ </indexterm>Selecting Power Management Software</title>
+ <para>Lustre failover requires RPC and management capability to verify that a failed node is
+ shut down before I/O is directed to the failover node. This avoids double-mounting the two
+ nodes and the risk of unrecoverable data corruption. A variety of power management tools
+ will work. Two packages that have been commonly used with the Lustre software are PowerMan
+ and Linux-HA (aka. STONITH ).</para>
+ <para>The PowerMan cluster power management utility is used to control
+ RPC devices from a central location. PowerMan provides native support
+ for several RPC varieties and Expect-like configuration simplifies
+ the addition of new devices. The latest versions of PowerMan are
+ available at: </para>
+ <para><link xmlns:xlink="http://www.w3.org/1999/xlink"
+ xlink:href="https://github.com/chaos/powerman">
+ https://github.com/chaos/powerman</link></para>
+ <para>STONITH, or “Shoot The Other Node In The Head”, is a set of power management tools
+ provided with the Linux-HA package prior to Red Hat Enterprise Linux 6. Linux-HA has native
+ support for many power control devices, is extensible (uses Expect scripts to automate
+ control), and provides the software to detect and respond to failures. With Red Hat
+ Enterprise Linux 6, Linux-HA is being replaced in the open source community by the
+ combination of Corosync and Pacemaker. For Red Hat Enterprise Linux subscribers, cluster
+ management using CMAN is available from Red Hat.</para>