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GANETI-MASTERD

GANETI-MASTERD

Section: (8) Updated: 16 July 2010
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NAME

ganeti-masterd - ganeti master daemon  

SYNOPSIS

ganeti-masterd [ -f ] [ -d ] [ --no-voting ]

 

DESCRIPTION

The ganeti-masterd is the daemon which is responsible for the overall cluster coordination. Without it, no change can be performed on the cluster.

For testing purposes, you can give the -f option and the program won't detach from the running terminal.

Debug-level message can be activated by giving the -d option.  

ROLE

The role of the master daemon is to coordinate all the actions that change the state of the cluster. Things like accepting new jobs, coordinating the changes on nodes (via RPC calls to the respective node daemons), maintaining the configuration and so on are done via this daemon.

The only action that can be done without the master daemon is the failover of the master role to another node in the cluster, via the gnt-cluster masterfailover command.

If the master daemon is stopped, the instances are not affected, but they won't be restarted automatically in case of failure.  

STARTUP

At startup, the master daemon will confirm with the node daemons that the node it is running is indeed the master node of the cluster. It will abort if it doesn't get half plus one positive answers (offline nodes are queried too, just in case our configuration is stale).

For small clusters with a number of nodes down, and especially for two-node clusters where the other has gone done, this creates a problem. In this case the --no-voting option can be used to skip this process. The option requires interactive confirmation, as having two masters on the same cluster is a very dangerous situation and will most likely lead to data loss.  

JOB QUEUE

The master daemon maintains a job queue (located under /var/lib/ganeti/queue) in which all current jobs are stored, one job per file serialized in JSON format; in this directory a subdirectory called archive holds archived job files.

The moving of jobs from the current to the queue directory is done via a request to the master; this can be accomplished from the command line with the gnt-job archive or gnt-job autoarchive commands. In case of problems with the master, a job file can simply be moved away or deleted (but this might leave the cluster inconsistent).  

COMMUNICATION PROTOCOL

The master accepts commands over a Unix socket, using JSON serialized messages separated by a specific byte sequence. For more details, see the design documentation supplied with Ganeti.  

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.


 

Index

NAME
SYNOPSIS
DESCRIPTION
ROLE
STARTUP
JOB QUEUE
COMMUNICATION PROTOCOL
REPORTING BUGS
SEE ALSO
COPYRIGHT

This document was created by man2html, using the manual pages.
Time: 22:01:40 GMT, April 16, 2011