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ganeti-watcher(8) Ganeti | Version @GANETI_VERSION@

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Name

----

ganeti-watcher - Ganeti cluster watcher

Synopsis

--------

**ganeti-watcher** [``--debug``]

[``--job-age=``*age*]

[``--ignore-pause``]

DESCRIPTION

-----------

The **ganeti-watcher** is a periodically run script which is

responsible for keeping the instances in the correct status. It has

two separate functions, one for the master node and another one

that runs on every node.

If the watcher is disabled at cluster level (via the

**gnt-cluster watcher pause** command), it will exit without doing

anything. The cluster-level pause can be overridden via the

``--ignore-pause`` option, for example if during a maintenance the

watcher needs to be disabled in general, but the administrator

wants to run it just once.

The ``--debug`` option will increase the verbosity of the watcher

and also activate logging to the standard error.

Master operations

~~~~~~~~~~~~~~~~~

Its primary function is to try to keep running all instances which

are marked as *up* in the configuration file, by trying to start

them a limited number of times.

Another function is to "repair" DRBD links by reactivating the

block devices of instances which have secondaries on nodes that

have been rebooted.

The watcher will also archive old jobs (older than the age given

via the ``--job-age`` option, which defaults to 6 hours), in order

to keep the job queue manageable.

Node operations

~~~~~~~~~~~~~~~

The watcher will restart any down daemons that are appropriate for

the current node.

In addition, it will execute any scripts which exist under the

"watcher" directory in the Ganeti hooks directory

(``@SYSCONFDIR@/ganeti/hooks``). This should be used for lightweight

actions, like starting any extra daemons.

If the cluster parameter ``maintain_node_health`` is enabled, then the

watcher will also shutdown instances and DRBD devices if the node is

declared as offline by known master candidates.

The watcher does synchronous queries but will submit jobs for

executing the changes. Due to locking, it could be that the jobs

execute much later than the watcher submits them.

FILES

-----

The command has a set of state files (one per group) located at

``@LOCALSTATEDIR@/lib/ganeti/watcher.GROUP-UUID.data`` (only used on the

master) and a log file at

``@LOCALSTATEDIR@/log/ganeti/watcher.log``. Removal of either file(s)

will not affect correct operation; the removal of the state file will

just cause the restart counters for the instances to reset to zero, and

mark nodes as freshly rebooted (so for example DRBD minors will be

re-activated).

In some cases, it's even desirable to reset the watcher state, for

example after maintenance actions, or when you want to simulate the

reboot of all nodes, so in this case, you can remove all state files:

.. code-block:: Bash

    rm -f @LOCALSTATEDIR@/lib/ganeti/watcher.*.data

    rm -f @LOCALSTATEDIR@/lib/ganeti/watcher.*.instance-status

    rm -f @LOCALSTATEDIR@/lib/ganeti/instance-status

And then re-run the watcher.

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