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       gfs_controld  -  daemon that manages mounting, unmounting, recovery and
       posix locks


       gfs_controld [OPTION]...


       GFS lives in  the  kernel,  and  the  cluster  infrastructure  (cluster
       membership  and  group  management)  lives  in  user space.  GFS in the
       kernel needs to adjust/recover for certain cluster  events.   It’s  the
       job  of  gfs_controld  to  receive  these events and reconfigure gfs as
       needed.  gfs_controld controls and configures gfs through  sysfs  files
       that are considered gfs-internal interfaces; not a general API/ABI.

       Mounting,  unmounting and node failure are the main cluster events that
       gfs_controld controls.  It also manages the assignment of  journals  to
       different  nodes.   The  mount.gfs  and umount.gfs programs communicate
       with gfs_controld  to  join/leave  the  mount  group  and  receive  the
       necessary options for the kernel mount.

       GFS   also   sends  all  posix  lock  operations  to  gfs_controld  for
       processing.  gfs_controld manages cluster-wide posix locks for gfs  and
       passes results back to gfs in the kernel.


       Optional   cluster.conf  settings  are  placed  in  the  <gfs_controld>

   Posix locks
       Heavy use of plocks can result in high network load.  The rate at which
       plocks are processed are limited by the plock_rate_limit setting, which
       limits the maximum plock performance, and limits potentially  excessive
       network  load.   This value is the maximum number of plock operations a
       single node will  process  every  second.   To  achieve  maximum  posix
       locking performance, the rate limiting should be disabled by setting it
       to 0.  The default value is 100.

         <gfs_controld plock_rate_limit="100"/>

       To optimize performance for repeated  locking  of  the  same  locks  by
       processes  on  a  single  node,  plock_ownership  can be set to 1.  The
       default is 0.  If this is  enabled,  gfs_controld  cannot  interoperate
       with older versions that did not support this option.

         <gfs_controld plock_ownership="1"/>

       Three  options  can be used to tune the behavior of the plock_ownership
       optimization.  All three relate to the caching of lock ownership state.
       Specifically,  they  define  how aggressively cached ownership state is
       dropped.   More  caching  of  ownership  state  can  result  in  better
       performance, at the expense of more memory usage.

       drop_resources_time  is the frequency of drop attempts in milliseconds.
       Default 10000 (10 sec).

       drop_resources_count is the maximum number of items to  drop  from  the
       cache each time.  Default 10.

       drop_resources_age  is the time in milliseconds a cached item should be
       unused before being considered for dropping.  Default 10000 (10 sec).

         <gfs_controld drop_resources_time="10000" drop_resources_count="10"


       -D     Run the daemon in the foreground and print debug  statements  to

       -P     Enable posix lock debugging messages.

       -w     Disable the "withdraw" feature.

       -p     Disable posix lock handling.

       -l <num>
              Limit  the  rate  at which posix lock messages are sent to <num>
              messages per second.  0 disables the limit and  results  in  the
              maximum performance of posix locks. Default 100.

       -o <num>
              Enable  (1) or disable (0) plock ownership optimization. Default
              0.  All nodes must run with the same value.

       -t <ms>
              Ownership cache  tuning,  drop  resources  time  (milliseconds).
              Default 10000.

       -c <ms>
              Ownership cache tuning, drop resources count. Default 10.

       -a <ms>
              Ownership  cache  tuning,  drop  resources  age  (milliseconds).
              Default 10000.

       -h     Print out a help  message  describing  available  options,  then

       -V     Print the version information and exit.


       The  gfs_controld daemon keeps a circular buffer of debug messages that
       can be dumped with the ’group_tool dump gfs’ command.

       The state of all gfs posix locks can also be dumped  from  gfs_controld
       with the ’group_tool dump plocks <fsname>’ command.


       groupd(8), group_tool(8)