Synnefo » snf-ganeti » ganeti-local

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  <!ENTITY dhdate      "<date>May 16, 2007</date>">

  <!-- SECTION should be 1-8, maybe w/ subsection other parameters are

       allowed: see man(7), man(1). -->

  <!ENTITY dhsection   "<manvolnum>8</manvolnum>">

  <!ENTITY dhucpackage "<refentrytitle>gnt-instance</refentrytitle>">

  <!ENTITY dhpackage   "gnt-instance">

  <!ENTITY debian      "<productname>Debian</productname>">

  <!ENTITY gnu         "<acronym>GNU</acronym>">

  <!ENTITY gpl         "&gnu; <acronym>GPL</acronym>">

  <!ENTITY footer SYSTEM "footer.sgml">

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<refentry>

  <refentryinfo>

    <copyright>

      <year>2006</year>

      <year>2007</year>

      <holder>Google Inc.</holder>

    </copyright>

    &dhdate;

  </refentryinfo>

  <refmeta>

    &dhucpackage;

    &dhsection;

    <refmiscinfo>ganeti 1.2</refmiscinfo>

  </refmeta>

  <refnamediv>

    <refname>&dhpackage;</refname>

    <refpurpose>ganeti instance administration</refpurpose>

  </refnamediv>

  <refsynopsisdiv>

    <cmdsynopsis>

      <command>&dhpackage; </command>

      <arg choice="req">command</arg>

      <arg>arguments...</arg>

    </cmdsynopsis>

  </refsynopsisdiv>

  <refsect1>

    <title>DESCRIPTION</title>

    <para>

      The <command>&dhpackage;</command> is used for instance

      administration in the ganeti system.

    </para>

  </refsect1>

  <refsect1>

    <title>COMMANDS</title>

    <refsect2>

      <title>Creation/removal/querying</title>

      <refsect3>

        <title>ADD</title>

        <cmdsynopsis>

          <command>add</command>

          <arg>-s <replaceable>disksize</replaceable></arg>

          <arg>--swap-size <replaceable>disksize</replaceable></arg>

          <arg>-m <replaceable>memsize</replaceable></arg>

          <sbr>

          <arg>-o <replaceable>os-type</replaceable></arg>

          <arg>-b <replaceable>bridge</replaceable></arg>

          <arg>--mac <replaceable>MAC-address</replaceable></arg>

          <arg>--hvm-boot-order <replaceable>boot-order</replaceable></arg>

          <sbr>

          <arg>--kernel <group choice="req">

              <arg>default</arg>

              <arg><replaceable>kernel_path</replaceable></arg>

            </group></arg>

          <sbr>

          <arg>--initrd <group choice="req">

              <arg>default</arg>

              <arg>none</arg>

              <arg><replaceable>initrd_path</replaceable></arg>

            </group> </arg>

          <sbr>

          <arg>--file-storage-dir <replaceable>dir_path</replaceable></arg>

          <arg>--file-driver <group choice="req">

              <arg>loop</arg>

              <arg>blktap</arg>

            </group></arg>

          <sbr>

          <arg choice="req">-t<group>

              <arg>diskless</arg>

              <arg>file</arg>

              <arg>plain</arg>

              <arg>drbd</arg>

            </group>

          </arg>

          <sbr>

          <arg choice="req">-n <replaceable>node<optional>:secondary-node</optional></replaceable></arg>

          <arg choice="req"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <para>

          Creates a new instance on the specified

          host. <replaceable>instance</replaceable> must be in DNS and

          resolve to a IP in the same network as the nodes in the

          cluster.

        </para>

        <para>

          The <option>-s</option> option specifies the disk size for

          the instance, in mebibytes (defaults to

          <constant>20480MiB</constant> =

          <constant>20GiB</constant>). You can also use one of the

          suffixes <literal>m</literal>, <literal>g</literal> or

          <literal>t</literal> to specificy the exact the units used;

          these suffixes map to mebibytes, gibibytes and tebibytes.

        </para>

        <para>

          The <option>--swap-size</option> option specifies the swap

          disk size (in mebibytes) for the instance (the one presented

          as <filename class="devicefile">/dev/sdb</filename>). The

          default is <constant>4096MiB</constant>. As for the disk

          size, you can specify other suffixes.

        </para>

        <para>

          The <option>-m</option> option specifies the memory size for

          the instance, in mebibytes (defaults to 128 MiB). Again, you

          can use other suffixes (e.g. <userinput>2g</userinput>).

        </para>

        <para>

          The <option>-o</option> options specifies the operating

          system to be installed. The available operating systems can

          be listed with <command>gnt-os list</command>.

        </para>

        <para>

          The <option>-b</option> option specifies the bridge to which the

          instance will be connected. (defaults to the cluster-wide default

          bridge specified at cluster initialization time).

        </para>

        <para>

          The <option>--mac</option> option specifies the MAC address

          of the ethernet interface for the instance. If this option

          is not specified, a new MAC address is generated randomly with

          the configured MAC prefix. The randomly generated MAC

          address is guaranteed to be unique among the instances of

          this cluster.

        </para>

        <para>

          The <option>--hvm-boot-order</option> option specifies the

          boot device order for Xen HVM instances. The boot order is a

          string of letters listing the boot devices, with valid

          device letters being:

        </para>

        <para>

          <variablelist>

            <varlistentry>

              <term>a</term>

              <listitem>

                <para>

                  floppy drive

                </para>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>c</term>

              <listitem>

                <para>

                  hard disk

                </para>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>d</term>

              <listitem>

                <para>

                  CDROM drive

                </para>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>n</term>

              <listitem>

                <para>

                  network boot (PXE)

                </para>

              </listitem>

            </varlistentry>

          </variablelist>

        </para>

        <para>

          The option is only relevant for Xen HVM instances and

          ignored by all other instances types.

        </para>

        <para>

          The <option>--kernel</option> options allows the instance to

          use a custom kernel (if a filename is passed) or to use the

          default kernel (<filename>@CUSTOM_XEN_KERNEL@</filename>), if the

          string <constant>default</constant> is passed.

        </para>

        <para>

          The <option>--initrd</option> option is similar: it allows

          the instance to use a custom initrd (if a filename is

          passed) or to use the default initrd

          (<filename>@CUSTOM_XEN_INITRD@</filename>), if the string

          <constant>default</constant> is passed, or to disable the

          use of an initrd, if the string <constant>none</constant> is

          passed. Note that in the case the instance is set to use the

          default initrd and it doesn't exist, it will be silently

          ignored; if the instance is set to use a custom initrd and

          it doesn't exist, this will be treated as an error and will

          prevent the startup of the instance.

        </para>

        <para>

          The <option>-t</option> options specifies the disk layout type for

          the instance. The available choices are:

          <variablelist>

            <varlistentry>

              <term>diskless</term>

              <listitem>

                <para>

                  This creates an instance with no disks. Its useful for

                  testing only (or other special cases).

                </para>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>file</term>

              <listitem>

                <para>Disk devices will be regular files.</para>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>plain</term>

              <listitem>

                <para>Disk devices will be logical volumes.</para>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>drbd</term>

              <listitem>

                <para>

                  Disk devices will be drbd (version 8.x) on top of

                  lvm volumes.

                </para>

              </listitem>

            </varlistentry>

          </variablelist>

        </para>

        <para>

          The optional second value of the <option>--node</option> is used for

          the remote raid template type and specifies the remote node.

        </para>

        <para>

          If you do not want gnt-instance to wait for the disk mirror

          to be synced, use the <option>--no-wait-for-sync</option>

          option.

        </para>

        <para>

          The <option>--file-storage-dir</option> specifies the relative path

          under the cluster-wide file storage directory to store file-based

          disks. It is useful for having different subdirectories for

          different instances. The full path of the directory where the disk

          files are stored will consist of cluster-wide file storage directory

          + optional subdirectory + instance name. Example:

          /srv/ganeti/file-storage/mysubdir/instance1.example.com. This option

          is only relevant for instances using the file storage backend.

        </para>

        <para>

          The <option>--file-driver</option> specifies the driver to use for

          file-based disks. Note that currently these drivers work with the

          xen hypervisor only. This option is only relevant for instances using

          the file storage backend. The available choices are:

          <variablelist>

            <varlistentry>

              <term>loop</term>

              <listitem>

                <para>Kernel loopback driver.</para>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>blktap</term>

              <listitem>

                <para>blktap driver.</para>

              </listitem>

            </varlistentry>

          <variablelist>

        </para>

        <para>

          The loop driver uses loopback devices to access the filesystem

          within the file. However, running I/O intensive applications

          in your instance using the loop driver might result in slowdowns.

          Furthermore, if you use the loopback driver consider increasing

          the maximum amount of loopback devices (on most systems it's 8)

          using the max_loop param.

        </para>

        <para>

          In order to be able to use the blktap driver you should check

          if the 'blktapctrl' user space disk agent is running (usually

          automatically started via xend). This user-level disk I/O

          interface has the advantage of better performance. Especially

          if you use a network file system (e.g. NFS) to store your instances

          this is the recommended choice.

        </para> 

        <para>

          Example:

          <screen>

# gnt-instance add -t file -s 30g -m 512 -o debian-etch \

  -n node1.example.com --file-storage-dir=mysubdir instance1.example.com

# gnt-instance add -t plain -s 30g -m 512 -o debian-etch \

  -n node1.example.com instance1.example.com

# gnt-instance add -t drbd -s 30g -m 512 -o debian-etch \

  -n node1.example.com:node2.example.com instance2.example.com

          </screen>

        </para>

      </refsect3>

      <refsect3>

        <title>REMOVE</title>

        <cmdsynopsis>

          <command>remove</command>

          <arg>--ignore-failures</arg>

          <arg choice="req"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <para>

          Remove an instance. This will remove all data from the

          instance and there is <emphasis>no way back</emphasis>. If

          you are not sure if you use an instance again, use

          <command>shutdown</command> first and leave it in the

          shutdown state for a while.

        </para>

        <para>

          The <option>--ignore-failures</option> option will cause the

          removal to proceed even in the presence of errors during the

          removal of the instance (e.g. during the shutdown or the

          disk removal). If this option is not given, the command will

          stop at the first error.

        </para>

        <para>

          Example:

          <screen>

# gnt-instance remove instance1.example.com

          </screen>

        </para>

      </refsect3>

      <refsect3>

        <title>LIST</title>

        <cmdsynopsis>

          <command>list</command>

          <arg>--no-headers</arg>

          <arg>--separator=<replaceable>SEPARATOR</replaceable></arg>

          <arg>-o <replaceable>[+]FIELD,...</replaceable></arg>

        </cmdsynopsis>

        <para>

          Shows the currently configured instances with memory usage,

          disk usage, the node they are running on, and the CPU time,

          counted in seconds, used by each instance since its latest

          restart.

        </para>

        <para>

          The <option>--no-headers</option> option will skip the

          initial header line. The <option>--separator</option> option

          takes an argument which denotes what will be used between

          the output fields. Both these options are to help scripting.

        </para>

        <para>

          The <option>-o</option> option takes a comma-separated list

          of output fields. The available fields and their meaning

          are:

          <variablelist>

            <varlistentry>

              <term>name</term>

              <listitem>

                <simpara>the instance name</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>os</term>

              <listitem>

                <simpara>the OS of the instance</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>pnode</term>

              <listitem>

                <simpara>the primary node of the instance</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>snodes</term>

              <listitem>

                <simpara>comma-separated list of secondary nodes for the

                  instance; usually this will be just one node</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>admin_state</term>

              <listitem>

                <simpara>the desired state of the instance (either "yes"

                  or "no" denoting the instance should run or

                  not)</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>admin_ram</term>

              <listitem>

                <simpara>the desired memory for the instance</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>disk_template</term>

              <listitem>

                <simpara>the disk template of the instance</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>oper_state</term>

              <listitem>

                <simpara>the actual state of the instance; can be

                one of the values "running", "stopped", "(node

                down)"</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>status</term>

              <listitem>

                <simpara>combined form of admin_state and oper_stat;

                this can be one of:

                <computeroutput>ERROR_nodedown</computeroutput> if the

                node of the instance is down,

                <computeroutput>ERROR_down</computeroutput> if the

                instance should run but is down,

                <computeroutput>ERROR_up</computeroutput> if the

                instance should be stopped but is actually running,

                <computeroutput>ADMIN_down</computeroutput> if the

                instance has been stopped (and is stopped) and

                <computeroutput>running</computeroutput> if the

                instance is set to be running (and is

                running)</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>oper_ram</term>

              <listitem>

                <simpara>the actual memory usage of the instance as seen

                  by the hypervisor</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>ip</term>

              <listitem>

                <simpara>the ip address ganeti recognizes as associated with

                the instance interface</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>mac</term>

              <listitem>

                <simpara>the instance interface MAC address</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>bridge</term>

              <listitem>

                <simpara>bridge the instance is connected to

                </simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>sda_size</term>

              <listitem>

                <simpara>the size of the instance's first disk</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>sdb_size</term>

              <listitem>

                <simpara>the size of the instance's second disk</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>vcpus</term>

              <listitem>

                <simpara>the number of VCPUs allocated to the

                instance</simpara>

              </listitem>

            </varlistentry>

          </variablelist>

        </para>

        <para>

          If the value of the option starts with the character

          <constant>+</constant>, the new fields will be added to the

          default list. This allows to quickly see the default list

          plus a few other fields, instead of retyping the entire list

          of fields.

        </para>

        <para>

          There is a subtle grouping about the available output

          fields: all fields except for <option>oper_state</option>,

          <option>oper_ram</option> and <option>status</option> are

          configuration value and not run-time values. So if you don't

          select any of the these fields, the query will be satisfied

          instantly from the cluster configuration, without having to

          ask the remote nodes for the data. This can be helpful for

          big clusters when you only want some data and it makes sense

          to specify a reduced set of output fields.

        </para>

        <para>The default output field list is:

          <simplelist type="inline">

            <member>name</member>

            <member>os</member>

            <member>pnode</member>

            <member>admin_state</member>

            <member>oper_state</member>

            <member>oper_ram</member>

          </simplelist>.

        </para>

      </refsect3>

      <refsect3>

        <title>INFO</title>

        <cmdsynopsis>

          <command>info</command>

          <arg rep="repeat"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <para>

          Show detailed information about the (given) instances. This

          is different from <command>list</command> as it shows

          detailed data about the instance's disks (especially useful

          for remote raid templates).

        </para>

      </refsect3>

      <refsect3>

        <title>MODIFY</title>

        <cmdsynopsis>

          <command>modify</command>

          <arg choice="opt">-m <replaceable>memsize</replaceable></arg>

          <arg choice="opt">-p <replaceable>vcpus</replaceable></arg>

          <arg choice="opt">-i <replaceable>ip</replaceable></arg>

          <arg choice="opt">-b <replaceable>bridge</replaceable></arg>

          <arg choice="opt">--mac <replaceable>MAC-address</replaceable></arg>

          <arg>--hvm-boot-order <replaceable>boot-order</replaceable></arg>

          <sbr>

          <arg>--kernel <group choice="req">

              <arg>default</arg>

              <arg><replaceable>kernel_path</replaceable></arg>

            </group></arg>

          <sbr>

          <arg>--initrd <group choice="req">

              <arg>default</arg>

              <arg>none</arg>

              <arg><replaceable>initrd_path</replaceable></arg>

            </group> </arg>

          <sbr>

          <arg choice="req"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <para>

          Modify the memory size, number of vcpus, ip address, MAC

          address and/or bridge for an instance.

        </para>

        <para>

          The memory size is given in MiB. Note that you need to give

          at least one of the arguments, otherwise the command

          complains.

        </para>

        <para>

          The <option>--kernel</option>, <option>--initrd</option>

          and <option>--hvm-boot-order</option>

          options are described in the <command>add</command> command.

        </para>

        <para>

          Additionally, the HVM boot order can be reset to the default

          values by using <option>--hvm-boot-order=default</option>.

        </para>

        <para>

          All the changes take effect at the next restart. If the

          instance is running, there is no effect on the instance.

        </para>

      </refsect3>

      <refsect3>

        <title>REINSTALL</title>

        <cmdsynopsis>

          <command>reinstall</command>

          <arg choice="opt">-o <replaceable>os-type</replaceable></arg>

          <arg choice="opt">-f <replaceable>force</replaceable></arg>

          <arg choice="req"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <para>

          Reinstalls the operating system on the given instance. The instance

          must be stopped when running this command. If the

          <option>--os-type</option> is specified, the operating system is

          changed.

        </para>

      </refsect3>

      <refsect3>

        <title>RENAME</title>

        <cmdsynopsis>

          <command>rename</command>

          <arg>--no-ip-check</arg>

          <arg choice="req"><replaceable>instance</replaceable></arg>

          <arg choice="req"><replaceable>new_name</replaceable></arg>

        </cmdsynopsis>

        <para>

          Renames the given instance. The instance must be stopped

          when running this command. The requirements for the new name

          are the same as for adding an instance: the new name must be

          resolvable and the IP it resolves to must not be reachable

          (in order to prevent duplicate IPs the next time the

          instance is started). The IP test can be skipped if the

          <option>--no-ip-check</option> option is passed.

        </para>

      </refsect3>

    </refsect2>

    <refsect2>

      <title>Starting/stopping/connecting to console</title>

      <refsect3>

        <title>STARTUP</title>

        <cmdsynopsis>

          <command>startup</command>

          <arg>--extra=<replaceable>PARAMS</replaceable></arg>

          <arg>--force</arg>

          <sbr>

          <group choice="opt">

            <arg>--instance</arg>

            <arg>--node</arg>

            <arg>--primary</arg>

            <arg>--secondary</arg>

            <arg>--all</arg>

          </group>

          <sbr>

          <arg choice="opt"

          rep="repeat"><replaceable>name</replaceable></arg>

        </cmdsynopsis>

        <para>

          Starts one or more instances, depending on the following

          options. The four available modes are:

          <variablelist>

            <varlistentry>

              <term><option>--instance</option></term>

              <listitem>

                <simpara>will start the instances given as arguments

                (at least one argument required); this is the default

                selection</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>--node</term>

              <listitem>

                <simpara>will start the instances who have the given

                node as either primary or secondary</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term><option>--primary</option></term>

              <listitem>

                <simpara>will start all instances whose primary node

                is in the list of nodes passed as arguments (at least

                one node required)</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term><option>--secondary</option></term>

              <listitem>

                <simpara>will start all instances whose secondary node

                is in the list of nodes passed as arguments (at least

                one node required)</simpara>

              </listitem>

            </varlistentry>

            <varlistentry>

              <term>--all</term>

              <listitem>

                <simpara>will start all instances in the cluster (no

                arguments accepted)</simpara>

              </listitem>

            </varlistentry>

          </variablelist>

        </para>

        <para>

          Note that although you can pass more than one selection

          option, the last one wins, so in order to guarantee the

          desired result, don't pass more than one such option.

        </para>

        <para>

          The <option>--extra</option> option is used to pass

          additional argument to the instance's kernel for this start

          only. Currently there is no way to specify a persistent set

          of arguments (beside the one hardcoded). Note that this may

          not apply to all virtualization types.

        </para>

        <para>

          Use <option>--force</option> to start even if secondary disks are

          failing.

        </para>

        <para>

          Example:

          <screen>

# gnt-instance start instance1.example.com

# gnt-instance start --extra single test1.example.com

# gnt-instance start --node node1.example.com node2.example.com

# gnt-instance start --all

          </screen>

        </para>

      </refsect3>

      <refsect3>

        <title>SHUTDOWN</title>

        <cmdsynopsis>

          <command>shutdown</command>

          <sbr>

          <group choice="opt">

            <arg>--instance</arg>

            <arg>--node</arg>

            <arg>--primary</arg>

            <arg>--secondary</arg>

            <arg>--all</arg>

          </group>

          <sbr>

          <arg choice="opt"

          rep="repeat"><replaceable>name</replaceable></arg>

        </cmdsynopsis>

        <para>

          Stops one or more instances. If the instance cannot be

          cleanly stopped during a hardcoded interval (currently 2

          minutes), it will forcibly stop the instance (equivalent to

          switching off the power on a physical machine).

        </para>

        <para>

          The <option>--instance</option>, <option>--node</option>,

          <option>--primary</option>, <option>--secondary</option> and

          <option>--all</option> options are similar as for the

          <command>startup</command> command and they influence the

          actual instances being shutdown.

        </para>

        <para>

          Example:

          <screen>

# gnt-instance shutdown instance1.example.com

# gnt-instance shutdown --all

          </screen>

        </para>

      </refsect3>

      <refsect3>

        <title>REBOOT</title>

        <cmdsynopsis>

          <command>reboot</command>

          <sbr>

          <arg>--extra=<replaceable>PARAMS</replaceable></arg>

          <sbr>

          <arg>--type=<replaceable>REBOOT-TYPE</replaceable></arg>

          <sbr>

          <arg>--ignore-secondaries</arg>

          <sbr>

          <arg>--force-multiple</arg>

          <sbr>

          <group choice="opt">

            <arg>--instance</arg>

            <arg>--node</arg>

            <arg>--primary</arg>

            <arg>--secondary</arg>

            <arg>--all</arg>

          </group>

          <sbr>

          <arg choice="opt"

          rep="repeat"><replaceable>name</replaceable></arg>

        </cmdsynopsis>

        <para>

          Reboots one or more instances. The type of reboot depends on

          the value of <option>--type</option>. A soft reboot does a

          hypervisor reboot, a hard reboot does a instance stop,

          recreates the hypervisor config for the instance and

          starts the instance. A full reboot does the equivalent

          of <command>gnt-instance shutdown &amp;&amp; gnt-instance

          startup</command>. The default is soft reboot.

        </para>

        <para>

          For the hard reboot the option

          <option>--ignore-secondaries</option> ignores errors for the

          secondary node while re-assembling the instance disks.

        </para>

        <para>

          The <option>--instance</option>, <option>--node</option>,

          <option>--primary</option>, <option>--secondary</option> and

          <option>--all</option> options are similar as for the

          <command>startup</command> command and they influence the

          actual instances being rebooted.

        </para>

        <para>

          Use the <option>--force-multiple</option> option to keep

          gnt-instance from asking for confirmation when more than one

          instance is affected.

        </para>

        <para>

          Example:

          <screen>

# gnt-instance reboot instance1.example.com

# gnt-instance reboot --type=full instance1.example.com

          </screen>

        </para>

      </refsect3>

      <refsect3>

        <title>CONSOLE</title>

        <cmdsynopsis>

          <command>console</command>

          <arg choice="opt">--show-cmd</arg>

          <arg choice="req"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <para>

          Connects to the console of the given instance. If the instance

          is not up, an error is returned. Use the <option>--show-cmd</option>

          option to display the command instead of executing it.

        </para>

        <para>

          Example:

          <screen>

# gnt-instance console instance1.example.com

          </screen>

        </para>

      </refsect3>

    </refsect2>

    <refsect2>

      <title>Disk management</title>

      <refsect3>

        <title>REPLACE-DISKS</title>

        <cmdsynopsis>

          <command>replace-disks</command>

          <arg choice="opt">--new-secondary <replaceable>NODE</replaceable></arg>

          <arg choice="req"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <cmdsynopsis>

          <command>replace-disks</command>

          <arg choice="opt">-s</arg>

          <arg choice="req">--new-secondary <replaceable>NODE</replaceable></arg>

          <arg choice="req"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <cmdsynopsis>

          <command>replace-disks</command>

          <group>

          <arg choice="req">-s</arg>

          <arg choice="req">-p</arg>

          </group>

          <arg choice="req"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <para>

          This command is a generalized form for adding and replacing

          disks.

        </para>

        <para>

          The first form is usable with the

          <literal>remote_raid1</literal> disk template. This will

          replace the disks on both the primary and secondary node,

          and optionally will change the secondary node to a new one

          if you pass the <option>--new-secondary</option> option.

        </para>

        <para>

          The second and third forms are usable with the

          <literal>drbd</literal> disk template. The second form will

          do a secondary replacement, but as opposed to the

          <literal>remote_raid1</literal> will not replace the disks

          on the primary, therefore it will execute faster. The third

          form will replace the disks on either the primary

          (<option>-p</option>) or the secondary (<option>-s</option>)

          node of the instance only, without changing the node.

        </para>

      </refsect3>

      <refsect3>

        <title>ACTIVATE-DISKS</title>

        <cmdsynopsis>

          <command>activate-disks</command>

          <arg choice="req"><replaceable>instance</replaceable></arg>

        </cmdsynopsis>

        <para>

          Activates the block devices of the given instance. If

          successful, the command will show the location and name of

          the block devices:

          <screen>

node1.example.com:sda:/dev/md0

node1.example.com:sdb:/dev/md1

          </screen>

          In this example, <emphasis>node1.example.com</emphasis> is

          the name of the node on which the devices have been

          activated. The <emphasis>sda</emphasis> and

          <emphasis>sdb</emphasis> are the names of the block devices

          inside the instance. <emphasis>/dev/md0</emphasis> and

          <emphasis>/dev/md1</emphasis> are the names of the block

          devices as visible on the node.

        </para>