NAME¶

dlm_controld - daemon that configures dlm according to cluster events

SYNOPSIS¶

dlm_controld [OPTIONS]

DESCRIPTION¶

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.

OPTIONS¶

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.

 

 

FILES¶

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.

Kernel options¶

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"/>

 

Daemon options¶

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"/>

 

 

Disabling resource directory¶

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>

Lock-server configuration¶

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.

SEE ALSO¶

dlm_tool(8), fenced(8), cman(5), cluster.conf(5)