Commit fde7c36c authored by Christos Stavrakakis's avatar Christos Stavrakakis
Browse files

docs: Add docs about disk_templates attribute

parent 667d82de
......@@ -603,6 +603,33 @@ between users and backends. If the user is found in ``BACKEND_PER_USER``, then
Synnefo allocates all his/hers VMs to the specific backend in the variable,
even if is marked as drained (useful for testing).
Allocation based on disk-templates
**********************************
Besides the available resources of each Ganeti backend, the allocator takes
into consideration the disk template of the instance when trying to allocate it
to a Ganeti backend. Specifically, the allocator checks if the flavor of the
instance belongs to the available disk templates of each Ganeti backend.
A Ganeti cluster has a list of enabled disk templates
(`--enabled-disk-templates`) and a list of allowed disk templates for new
instances (`--ipolicy-disk-templates`). See the `gnt-cluster` manpage for more
details about these options.
When Synnefo allocates an instance, it checks whether the disk template of the
new instance belongs both in the enabled and ipolicy disk templates. You can
see the list of the available disk-templates by running `snf-manage
backend-list`. This list should be updated automatically after changing
these options in Ganeti and it can also be updated by running `snf-manage
backend-update-status`.
So the administrator, can route instances on different backends based on their
flavor disk template, by modifying the enabled or ipolicy disk templates of
each backend. Also, the administrator can route instances between different
nodes of the same Ganeti backend, by modifying the same options at the
nodegroup level (see `gnt-group` manpage for mor details).
Managing Virtual Machines
~~~~~~~~~~~~~~~~~~~~~~~~~
......
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