The above command has the minimum required options; other options you
can give include, among others:
-- The memory size (``-B memory``)
+- The maximum/minimum memory size (``-B maxmem``, ``-B minmem``)
+ (``-B memory`` can be used to specify only one size)
- The number of virtual CPUs (``-B vcpus``)
gnt-instance remove INSTANCE_NAME
+.. _instance-startup-label:
+
Startup/shutdown
~~~~~~~~~~~~~~~~
gnt-instance startup INSTANCE_NAME
+Ganeti will start an instance with up to its maximum instance memory. If
+not enough memory is available Ganeti will use all the available memory
+down to the instance minumum memory. If not even that amount of memory
+is free Ganeti will refuse to start the instance.
+
Note, that this will not work when an instance is in a permanently
stopped state ``offline``. In this case, you will first have to
put it back to online mode by running::
does not require dynamically allocated resources (memory and vcpus),
after shutting down an instance, execute the following::
- gnt-instance modify --ofline INSTANCE_NAME
+ gnt-instance modify --offline INSTANCE_NAME
.. warning:: Do not use the Xen or KVM commands directly to stop
instances. If you run for example ``xm shutdown`` or ``xm destroy``
status), etc. This is harder to parse and is more expensive than the
list operation, but returns much more detailed information.
+Changing an instance's runtime memory
++++++++++++++++++++++++++++++++++++++
+
+Ganeti will always make sure an instance has a value between its maximum
+and its minimum memory available as runtime memory. As of version 2.6
+Ganeti will only choose a size different than the maximum size when
+starting up, failing over, or migrating an instance on a node with less
+than the maximum memory available. It won't resize other instances in
+order to free up space for an instance.
+
+If you find that you need more memory on a node any instance can be
+manually resized without downtime, with the command::
+
+ gnt-instance modify -m SIZE INSTANCE_NAME
+
+The same command can also be used to increase the memory available on an
+instance, provided that enough free memory is available on its node, and
+the specified size is not larger than the maximum memory size the
+instance had when it was first booted (an instance will be unable to see
+new memory above the maximum that was specified to the hypervisor at its
+boot time, if it needs to grow further a reboot becomes necessary).
Export/Import
+++++++++++++
That's it. After the command completes the secondary node is now the
primary, and vice-versa.
+The instance will be started with an amount of memory between its
+``maxmem`` and its ``minmem`` value, depending on the free memory on its
+target node, or the operation will fail if that's not possible. See
+:ref:`instance-startup-label` for details.
+
Live migrating an instance
~~~~~~~~~~~~~~~~~~~~~~~~~~
long the migration will take. In any case, for both KVM and Xen
hypervisors, the migration will be transparent to the instance.
+If the destination node has less memory than the instance's current
+runtime memory, but at least the instance's minimum memory available
+Ganeti will automatically reduce the instance runtime memory before
+migrating it, unless the ``--no-runtime-changes`` option is passed, in
+which case the target node should have at least the instance's current
+runtime memory free.
+
Moving an instance (offline)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~