openstack-manuals/doc/common/section_support-compute.xml
Summer Long f07897895a Added info on Guru Meditation reports for Compute
New section under Troubleshooting.
Related dev change is: I224a426dad084f0e738069207ffbffe7f7935a17

Closes-Bug: #1303253

Change-Id: I74c70289eb57c805ed0c582572802d39425f6964
2014-04-07 20:29:18 +10:00

232 lines
13 KiB
XML

<!DOCTYPE section [
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<section 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"
xml:id="section_compute-troubleshooting">
<title>Troubleshoot Compute</title>
<para>Common problems for Compute typically involve misconfigured
networking or credentials that are not sourced properly in the
environment. Also, most flat networking configurations do not
enable <command>ping</command> or <command>ssh</command> from
a compute node to the instances that run on that node. Another
common problem is trying to run 32-bit images on a 64-bit
compute node. This section shows you how to troubleshoot
Compute.</para>
<section xml:id="log-files-for-openstack-compute">
<title>Compute service logging</title>
<para>Compute stores a log file for each service in
<filename>/var/log/nova</filename>. For example,
<filename>nova-compute.log</filename> is the log for
the <systemitem class="service">nova-compute</systemitem>
service. You can set the following options to format log
strings for the nova.log module in the
<filename>nova.conf</filename> file:</para>
<itemizedlist>
<listitem>
<para><literal>logging_context_format_string</literal></para>
</listitem>
<listitem>
<para><literal>logging_default_format_string</literal></para>
</listitem>
</itemizedlist>
<para>If the log level is set to <literal>debug</literal>, you
can also specify
<literal>logging_debug_format_suffix</literal> to
append extra formatting. For information about what
variables are available for the formatter see: <link
xlink:href="http://docs.python.org/library/logging.html#formatter"
>http://docs.python.org/library/logging.html#formatter</link>.</para>
<para>You have two options for logging for OpenStack Compute
based on configuration settings. In
<filename>nova.conf</filename>, include the
<literal>logfile</literal> option to enable logging.
Alternatively you can set <literal>use_syslog=1</literal>
so that the nova daemon logs to syslog.</para>
</section>
<section xml:id="section_compute-GuruMed-reports">
<title>Guru Meditation reports</title>
<para>A Guru Meditation report is sent by the Compute Service upon receipt of the
<systemitem>SIGUSR1</systemitem> signal. This report is a general-purpose error
report, including a complete report of the service's current state, and is sent to
<systemitem>stderr</systemitem>.</para>
<para>For example, if you redirect error output to <filename>nova-api-err.log</filename>
using <command>nova-api 2&gt;/var/log/nova/nova-api-err.log</command>, resulting in the
process ID 8675, you can then run:</para>
<screen><prompt>#</prompt> <userinput>kill -USR1 8675</userinput></screen>
<para>This command triggers the Guru Meditation report to be printed to
<filename>/var/log/nova/nova-api-err.log</filename>.</para>
<para>The report has the following sections:
<itemizedlist>
<listitem><para>Package &mdash; Displays information about the package to which
the process belongs, including version information.</para></listitem>
<listitem><para>Threads &mdash; Displays stack traces and thread IDs for each of the threads within the
process.</para></listitem>
<listitem><para>Green Threads &mdash; Displays stack traces for each of the green
threads within the process (green threads do not have thread IDs).</para></listitem>
<listitem><para>Configuration &mdash; Lists all configuration options currently accessible through the CONF
object for the current process.</para></listitem>
</itemizedlist></para>
<para>For more information, see <link
xlink:href="http://docs.openstack.org/developer/nova/devref/gmr.html"
>Guru Meditation Reports</link>.</para>
</section>
<section xml:id="section_compute-common-errors-and-fixes">
<title>Common errors and fixes for Compute</title>
<para>The <link xlink:href="ask.openstack.org"
>ask.openstack.org</link> site offers a place to ask
and answer questions, and you can also mark questions as
frequently asked questions. This section describes some
errors people have posted previously. Bugs are constantly
being fixed, so online resources are a great way to get
the most up-to-date errors and fixes.</para>
<section xml:id="section_credential-errors">
<title>Credential errors, 401, and 403 forbidden
errors</title>
<para>Missing credentials cause a
<errorcode>403</errorcode>
<errortext>forbidden</errortext> error. To resolve
this issue, use one of these methods:<orderedlist>
<listitem>
<para><emphasis role="bold">Manual
method</emphasis>. Get get the
<filename>novarc</filename> file from
the project ZIP file, save existing
credentials in case of override. and
manually source the
<filename>novarc</filename>
file.</para>
</listitem>
<listitem>
<para><emphasis role="bold">Script
method</emphasis>. Generates
<filename>novarc</filename> from the
project ZIP file and sources it for
you.</para>
</listitem>
</orderedlist></para>
<para>When you run <systemitem class="service"
>nova-api</systemitem> the first time, it
generates the certificate authority information,
including <filename>openssl.cnf</filename>. If you
start the CA services before this, you might not be
able to create your ZIP file. Restart the services.
When your CA information is available, create your ZIP
file.</para>
<para>Also, check your HTTP proxy settings to see whether
they cause problems with <filename>novarc</filename>
creation.</para>
</section>
<section xml:id="section_instance-errors">
<title>Instance errors</title>
<para>Sometimes a particular instance shows
<literal>pending</literal> or you cannot SSH to
it. Sometimes the image itself is the problem. For
example, when you use flat manager networking, you do
not have a DHCP server and certain images do not
support interface injection; you cannot connect to
them. The fix for this problem is to use an image that
does support this method, such as Ubuntu, which
obtains an IP address correctly with FlatManager
network settings.</para>
<para>To troubleshoot other possible problems with an
instance, such as an instance that stays in a spawning
state, check the directory for the particular instance
under <filename>/var/lib/nova/instances</filename> on
the <systemitem class="service"
>nova-compute</systemitem> host and make sure that
these files are present:</para>
<itemizedlist>
<listitem>
<para><filename>libvirt.xml</filename></para>
</listitem>
<listitem>
<para><filename>disk</filename></para>
</listitem>
<listitem>
<para><filename>disk-raw</filename></para>
</listitem>
<listitem>
<para><filename>kernel</filename></para>
</listitem>
<listitem>
<para><filename>ramdisk</filename></para>
</listitem>
<listitem>
<para>After the instance starts,
<filename>console.log</filename></para>
</listitem>
</itemizedlist>
<para>If any files are missing, empty, or very small, the
<systemitem class="service"
>nova-compute</systemitem> service did not
successfully download the images from the Image
Service.</para>
<para>Also check <filename>nova-compute.log</filename> for
exceptions. Sometimes they do not appear in the
console output.</para>
<para>Next, check the log file for the instance in the
<filename>/var/log/libvirt/qemu</filename>
directory to see if it exists and has any useful error
messages in it.</para>
<para>Finally, from the
<filename>/var/lib/nova/instances</filename>
directory for the instance, see if this command
returns an error:</para>
<screen><prompt>#</prompt> <userinput>virsh create libvirt.xml</userinput></screen>
</section>
<section xml:id="section_compute-empty-log-output">
<title>Empty log output for Linux instances</title>
<para>You can view the log output of running instances
from either the <guilabel>Log</guilabel> tab of the
dashboard or the output of
<command>nova console-log</command>. In some cases, the
log output of a running Linux instance will be empty or
only display a single character (for example,
the <keycap>?</keycap> character).</para>
<para>This occurs when the Compute service attempts to
retrieve the log output of the instance via a serial
console while the instance itself is not configured to
send output to the console. To rectify this, append the
following parameters to kernel arguments specified in the
instance's boot loader:</para>
<screen>console=tty0 console=ttyS0,115200n8</screen>
<para>Upon rebooting, the instance will be configured to
send output to the Compute service.</para>
</section>
</section>
<section xml:id="reset-state">
<title>Reset the state of an instance</title>
<para>If an instance remains in an intermediate state, such as
<literal>deleting</literal>, you can use the
<command>nova reset-state</command> command to
manually reset the state of an instance to an error state.
You can then delete the instance. For example:</para>
<screen><prompt>$</prompt> <userinput>nova reset-state c6bbbf26-b40a-47e7-8d5c-eb17bf65c485</userinput>
<prompt>$</prompt> <userinput>nova delete c6bbbf26-b40a-47e7-8d5c-eb17bf65c485</userinput></screen>
<para>You can also use the <parameter>--active</parameter>
parameter to force the instance back to an active state
instead of an error state. For example:</para>
<screen><prompt>$</prompt> <userinput>nova reset-state --active c6bbbf26-b40a-47e7-8d5c-eb17bf65c485</userinput></screen>
</section>
<section xml:id="problems-with-injection">
<title>Injection problems</title>
<para>If instances do not boot or boot slowly, investigate
file injection as a cause.</para>
<para>To disable injection in libvirt, set
<option>libvirt_inject_partition</option> to
<literal>-2</literal>.</para>
<note>
<para>If you have not enabled the configuration drive and
you want to make user-specified files available from
the metadata server for to improve performance and
avoid boot failure if injection fails, you must
disable injection.</para>
</note>
</section>
</section>