Ubuntu Manpage: ganeti-watcher - Ganeti cluster watcher

Provided by: ganeti-2.16_2.16.0~rc2-1build1_all

Name

       ganeti-watcher - Ganeti cluster watcher

Synopsis

       ganeti-watcher    [--debug]    [--job-age=*age*    ]   [--ignore-pause]   [--rapi-ip=*IP*]
       [--no-verify-disks]

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.

The --rapi-ip option needs to be set if the RAPI daemon was started with a particular IP
(using the -b option). The two options need to be exactly the same to ensure that the
watcher can reach the RAPI interface.

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.

Additionally, it will verify and repair degraded DRBD disks; this will not happen, if the
--no-verify-disks option is given.

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 (/etc/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
       /var/lib/ganeti/watcher.GROUP-UUID.data (only used on  the  master)  and  a  log  file  at
       /var/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:

              rm -f /var/lib/ganeti/watcher.*.data
              rm -f /var/lib/ganeti/watcher.*.instance-status
              rm -f /var/lib/ganeti/instance-status

       And then re-run the watcher.

REPORTING BUGS

       Report  bugs  to  project  website  (http://code.google.com/p/ganeti/)  or   contact   the
       developers using the Ganeti mailing list (ganeti@googlegroups.com).

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