Algorithm options:
**[ -G *name* ]**
-
**[ -O *name...* ]**
+**[ --node-tags** *tag,..* **]**
+**[ --skip-non-redundant ]**
+
+**[ --offline-maintenance ]**
+**[ --ignore-non-redundant ]**
Reporting options:
**[ -v... | -q ]**
**[ -S *file* ]**
+**[ --one-step-only ]**
+**[ --print-moves ]**
DESCRIPTION
-----------
which set of nodes can be rebooted at the same time while avoiding
having both primary and secondary nodes being rebooted at the same time.
-For backends that support identifying the master node (currenlty
+For backends that support identifying the master node (currently
RAPI and LUXI), the master node is scheduled as the last node
-in the last reboot group.
+in the last reboot group. Apart from this restriction, larger reboot
+groups are put first.
ALGORITHM FOR CALCULATING OFFLINE REBOOT GROUPS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
hroller will view the nodes as vertices of an undirected graph,
-connecting by instances which have both a primary and a secondary node.
-It will then color the graph using a few different heuristics, and
-return the minimum-size color set found. Node with the same color don't
-share an edge, and as such don't have an instance with both primary and
-secondary node on them, so they are safe to be rebooted concurrently.
+with two kind of edges. Firstly, there are edges from the primary
+to the secondary node of every instance. Secondly, two nodes are connected
+by an edge if they are the primary nodes of two instances that have the
+same secondary node. It will then color the graph using a few different
+heuristics, and return the minimum-size color set found. Node with the same
+color can then simultaneously migrate all instance off to their respective
+secondary nodes, and it is safe to reboot them simultaneously.
OPTIONS
-------
\--force
Do not fail, even if the master node cannot be determined.
+\--node-tags *tag,...*
+ Restrict to nodes having at least one of the given tags.
+
+\--full-evacuation
+ Also plan moving secondaries out of the nodes to be rebooted. For
+ each instance the move is at most a migrate (if it was primary
+ on that node) followed by a replace secondary.
+
+\--skip-non-redundant
+ Restrict to nodes not hosting any non-redundant instance.
+
+\--offline-maintenance
+ Pretend that all instances are shutdown before the reboots are carried
+ out. I.e., only edges from the primary to the secondary node of an instance
+ are considered.
+
+\--ignore-non-redundnant
+ Pretend that the non-redundant instances do not exist, and only take
+ instances with primary and secondary node into account.
+
+\--one-step-only
+ Restrict to the first reboot group. Output the group one node per line.
+
+\--print-moves
+ After each group list for each affected instance a node
+ where it can be evacuated to. The moves are computed under the assumption
+ that after each reboot group, all instances are moved back to their
+ initial position.
+
BUGS
----
-Offline nodes should be ignored.
-
If instances are online the tool should refuse to do offline rolling
maintenances, unless explicitly requested.
End-to-end shelltests should be provided.
-Online rolling maintenances (where instance need not be shut down, but
-are migrated from node to node) are not supported yet. Hroller by design
-should support them both with and without secondary node replacement.
+EXAMPLES
+--------
+
+Online Rolling reboots, using tags
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Selecting by tags and getting output for one step only can be used for
+planing the next maintenance step.
+::
+
+ $ hroller --node-tags needsreboot --one-step-only -L
+ 'First Reboot Group'
+ node1.example.com
+ node3.example.com
+
+Typically these nodes would be drained and migrated.
+::
+
+ $ GROUP=`hroller --node-tags needsreboot --one-step-only --no-headers -L`
+ $ for node in $GROUP; do gnt-node modify -D yes $node; done
+ $ for node in $GROUP; do gnt-node migrate -f --submit $node; done
+
+After maintenance, the tags would be removed and the nodes undrained.
-EXAMPLE
--------
Offline Rolling node reboot output
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-With the default options, the program shows one reboot group per line as
-a comma-separated list.
+If all instances are shut down, usually larger node groups can be found.
::
- $ hroller -L
+ $ hroller --offline-maintainance -L
'Node Reboot Groups'
node1.example.com,node3.example.com,node5.example.com
node8.example.com,node6.example.com,node2.example.com
node7.example.com,node4.example.com
+Rolling reboots with non-redundant instances
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+By default, hroller plans capacity to move the non-redundant instances
+out of the nodes to be rebooted. If requested, apropriate locations for
+the non-redundant instances can be shown. The assumption is that instances
+are moved back to their original node after each reboot; these back moves
+are not part of the output.
+::
+
+ $ hroller --print-moves -L
+ 'Node Reboot Groups'
+ node-01-002,node-01-003
+ inst-20 node-01-001
+ inst-21 node-01-000
+ inst-30 node-01-005
+ inst-31 node-01-004
+ node-01-004,node-01-005
+ inst-40 node-01-001
+ inst-41 node-01-000
+ inst-50 node-01-003
+ inst-51 node-01-002
+ node-01-001,node-01-000
+ inst-00 node-01-002
+ inst-01 node-01-003
+ inst-10 node-01-005
+ inst-11 node-01-004
+
+
+
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projects / ganeti-local / blobdiff