Daemon that configures dlm according to cluster events
dlm_controld [OPTIONS]
The dlm lives in the kernel, and the cluster infrastructure (corosync membership and group management) lives in user space. The dlm in the kernel needs to adjust/recover for certain cluster events. It's the job of dlm_controld to receive these events and reconfigure the kernel dlm as needed. dlm_controld controls and configures the dlm through sysfs and configfs files that are considered dlm-internal interfaces.
The cman init script usually starts the dlm_controld daemon.
Command line options override a corresponding setting in cluster.conf.
-D
Enable debugging to stderr and don't fork.
See also dlm_tool dump in dlm_tool(8).
-L
Enable debugging to log file.
See also logging in cluster.conf(5).
-K
Enable kernel dlm debugging messages.
See also log_debug below.
-r num
dlm kernel lowcomms protocol, 0 tcp, 1 sctp, 2 detect. 2 selects tcp if corosync rrp_mode is "none", otherwise sctp.
Default 2.
-g num
groupd compatibility mode, 0 off, 1 on.
Default 0.
-f num
Enable (1) or disable (0) fencing recovery dependency.
Default 1.
-q num
Enable (1) or disable (0) quorum recovery dependency.
Default 0.
-d num
Enable (1) or disable (0) deadlock detection code.
Default 0.
-p num
Enable (1) or disable (0) plock code for cluster fs.
Default 1.
-l num
Limit the rate of plock operations, 0 for no limit.
Default 0.
-o num
Enable (1) or disable (0) plock ownership.
Default 1.
-t ms
Plock ownership drop resources time (milliseconds).
Default 10000.
-c num
Plock ownership drop resources count.
Default 10.
-a ms
Plock ownership drop resources age (milliseconds).
Default 10000.
-P
Enable plock debugging messages (can produce excessive output).
-h
Print a help message describing available options, then exit.
-V
Print program version information, then exit.
cluster.conf(5) is usually located at /etc/cluster/cluster.conf. It is not read directly. Other cluster components load the contents into memory, and the values are accessed through the libccs library.
Configuration options for dlm (kernel) and dlm_controld are added to the <dlm /> section of cluster.conf, within the top level <cluster> section.
protocol
The network protocol can be set to tcp, sctp or detect which selects tcp or sctp based on the corosync rrp_mode configuration (redundant ring protocol). The rrp_mode "none" results in tcp. Default detect.
<dlm protocol="detect"/>
timewarn
After waiting timewarn centiseconds, the dlm will emit a warning via netlink. This only applies to lockspaces created with the DLM_LSFL_TIMEWARN flag, and is used for deadlock detection. Default 500 (5 seconds).
<dlm timewarn="500"/>
log_debug
DLM kernel debug messages can be enabled by setting log_debug to 1. Default 0.
<dlm log_debug="0"/>
clusternode/weight
The lock directory weight can be specified one the clusternode lines. Weights would usually be used in the lock server configurations shown below instead.
<clusternode name="node01" nodeid="1" weight="1"/>
enable_fencing
See command line description.
<dlm enable_fencing="1"/>
enable_quorum
See command line description.
<dlm enable_quorum="0"/>
enable_deadlk
See command line description.
<dlm enable_deadlk="0"/>
enable_plock
See command line description.
<dlm enable_plock="1"/>
plock_rate_limit
See command line description.
<dlm plock_rate_limit="0"/>
plock_ownership
See command line description.
<dlm plock_ownership="1"/>
drop_resources_time
See command line description.
<dlm drop_resources_time="10000"/>
drop_resources_count
See command line description.
<dlm drop_resources_count="10"/>
drop_resources_age
See command line description.
<dlm drop_resources_age="10000"/>
plock_debug
Enable (1) or disable (0) plock debugging messages (can produce excessive output). Default 0.
<dlm plock_debug="0"/>
Lockspaces usually use a resource directory to keep track of which node is the master of each resource. The dlm can operate without the resource directory, though, by statically assigning the master of a resource using a hash of the resource name. To enable, set the per-lockspace nodir option to 1.
<dlm> <lockspace name="foo" nodir="1"/> </dlm>
The nodir setting can be combined with node weights to create a configuration where select node(s) are the master of all resources/locks. These master nodes can be viewed as "lock servers" for the other nodes.
<dlm>
<lockspace name="foo" nodir="1">
<master name="node01"/>
</lockspace>
</dlm>
or,
<dlm>
<lockspace name="foo" nodir="1">
<master name="node01"/>
<master name="node02"/>
</lockspace>
</dlm>
Lock management will be partitioned among the available masters. There can be any number of masters defined. The designated master nodes will master all resources/locks (according to the resource name hash). When no masters are members of the lockspace, then the nodes revert to the common fully-distributed configuration. Recovery is faster, with little disruption, when a non-master node joins/leaves.
There is no special mode in the dlm for this lock server configuration, it's just a natural consequence of combining the "nodir" option with node weights. When a lockspace has master nodes defined, the master has a default weight of 1 and all non-master nodes have weight of 0. An explicit non-zero weight can also be assigned to master nodes, e.g.
<dlm>
<lockspace name="foo" nodir="1">
<master name="node01" weight="2"/>
<master name="node02" weight="1"/>
</lockspace>
</dlm>
In which case node01 will master 2/3 of the total resources and node2 will master the other 1/3.