NAME
ganeti-watcher - ganeti cluster watcher
SYNOPSIS
ganeti-watcher
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.
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.
Its other function is to ‘‘repair’’ DRBD links by reactivating the
block devices of instances which have secondaries on nodes that have
been rebooted.
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 executes them.
FILES
The command has a state file located at /var/lib/ganeti/watcher.data
(only used on the master) and a log file at
/var/log/ganeti/watcher.log. Removal of either file will not affect
correct operation; the removal of the state file will just cause the
restart counters for the instances to reset to zero.
REPORTING BUGS
Report bugs to <URL: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 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-
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).
COPYRIGHT
Copyright (C) 2006, 2007, 2008, 2009 Google Inc. Permission is granted
to copy, distribute and/or modify under the terms of the GNU General
Public License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
On Debian systems, the complete text of the GNU General Public License
can be found in /usr/share/common-licenses/GPL.