Ubuntu Manpage: ganeti-watcher - Ganeti cluster watcher

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 (/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).

       Ganeti  overview  and  specifications:  ganeti(7)  (general  overview),  ganeti-os-interface(7) (guest OS
       definitions), ganeti-extstorage-interface(7) (external storage providers).

       Ganeti commands: gnt-cluster(8) (cluster-wide commands), gnt-job(8) (job-related  commands),  gnt-node(8)
       (node-related  commands),  gnt-instance(8)  (instance  commands),  gnt-os(8)  (guest  OS  commands), gnt-
       storage(8) (storage commands), gnt-group(8) (node group commands), gnt-backup(8) (instance  import/export
       commands), gnt-debug(8) (debug commands).

       Ganeti  daemons: ganeti-watcher(8) (automatic instance restarter), ganeti-cleaner(8) (job queue cleaner),
       ganeti-noded(8) (node daemon), ganeti-masterd(8) (master daemon), ganeti-rapi(8) (remote API daemon).

       Ganeti htools: htools(1) (generic binary), hbal(1) (cluster balancer), hspace(1) (capacity  calculation),
       hail(1) (IAllocator plugin), hscan(1) (data gatherer from remote clusters), hinfo(1) (cluster information
       printer), mon-collector(7) (data collectors interface).

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