Provided by: ganeti-2.16_2.16.1-2ubuntu1_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 (@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:
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.
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).
SEE ALSO
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-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).
COPYRIGHT
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