Purpose
Creates a new communication group
definition for a peer domain.
Syntax
mkcomg [-s sensitivity]
[-p period ]
[ -g grace ] [-t priority]
[ -x b | r | br ]
[ -N UseForNodeMembership ] [-e NIM_path]
[-m NIM_parameters ]
[ -M media_type ] [ -i {h | n}:interface1[:node1][,interface2[:node2]...]
| -S {h | n}:"interface_selection_string" [ -6 ]
[-h] [-TV] communication_group
Description
The mkcomg command
creates a new communication group definition for an online peer domain
with the name specified by the communication_group parameter.
The communication group is used to define heartbeat rings for use
by topology services and to define the tunables for each heartbeat
ring. The communication group determines which devices are used for
heartbeating in the peer domain. There can be more than one communication
group in a peer domain.
The mkcomg command
must be run on a node that is currently online in the peer domain
where the communication group is to be defined. More than half of
the nodes must be online to create a new communication group for the
domain.
The -e and -m flags
are used to set the network interface module (NIM) path and parameters.
The NIM path is the path to the NIM that supports the adapter types
used in the communication group. The NIM parameters are passed to
NIM when it is started. If -m is not specified,
the parameters predefined by topology services are used.
The
communication group can be assigned to one or more interface resources.
Use the -i flag to assign the communication
group to a specific interface resource name. The interface resource
can be limited to one on a particular node. An interface resource
can also be specified using the -S flag
and a selection string. This is used when specifying the interface
resource name is not sufficient. The -i and
-S flags cannot be used together. The chcomg command
can also be used to assign a communication group to an interface resource.
Flags
- -s sensitivity
- Specifies the heartbeat sensitivity. This is the number of missed
heartbeats that constitute a failure. The sensitivity value is an
integer greater than or equal to 2. The default value is 4.
- -p period
- Specifies the amount of time between heartbeats. The period is
specified in seconds and is significant to milliseconds. It can be
specified as an integer or as a floating-point number.
- -g grace
- Specifies the grace period that is used when heartbeats are no
longer received. When a heartbeat is missed, an Internet Control Message
Protocol (ICMP) echo packet is sent to the failed node. If the echo
is returned, the grace period is initiated.
The grace period is
specified in seconds and is significant to milliseconds. It can be
specified as an integer, a floating-point number, or one of these
values:
- 0
- Specifies that the grace period is disabled.
- -1 | D
- Specifies that the topology services subsystem controls the grace
period. This is the default.
- -t priority
- Specifies the priority. This value indicates the importance of
this communication group with respect to others. It is used to order
the heartbeat rings. The lower the number means the higher the priority.
The highest priority is 1. The default value is 1 for IP networks
and 255 for RS232 networks.
- -x b | r | br
- Excludes controls for heartbeat mechanisms. This flag indicates
that one or more controls for heartbeat mechanisms should not be
used even if the underlying media support it. The following features
can be excluded:
- b
- Specifies that the broadcast feature should not be used even if
the underlying media support it. If -x b is
not specified, the broadcast feature will be used if the underlying
media support it.
- r
- Specifies that the source routing feature should not be used even
if the underlying media support it. If -x r is
not specified, the source routing feature will be used if the underlying
media support it.
To exclude more than one control, specify the feature
characters consecutively: -x br.
- -N UseForNodeMembership
- Specifies whether group services will use the communication group
in calculating node membership. Sets the UseForNodeMembership persistent
resource attribute for the communication group resource. Valid values
are:
- 0
- Indicates that, regardless of the results of liveness checks run
on NetworkInterface resources that are members of this communication
group, group services will not use those results in calculating whether
the node owning the interfaces is online.
- 1
- Indicates that group services will use the results of liveness
checks run on the NetworkInterface resources in calculating
the online state of their owning nodes.
- -e NIM_path
- Specifies the network interface module (NIM) path name. This
character string specifies the path name to the NIM that supports
the adapter types in the communication group.
- -m NIM_parameters
- Specifies the NIM start parameters. This character string is
passed to the NIM when starting it.
- -M media_type
- Specifies the type of interfaces that make up communication_group.
Valid values are:
- 0
- Indicates that communication_group consists of interface
resources other than IP or disk.
- 1
- Indicates that communication_group consists of IPv4 or
IPv6 interface resources.
If the -M flag is not specified,
this is the default.
- 2
- Indicates that communication_group consists of disk interface
resources.
- -i {h | n}:interface1[:node1]
[,interface2[:node2]...
- Assigns communication_group to one or more heartbeat or
network interface resources and, optionally, to the nodes where these
resources can be found. Specify -i h for heartbeat interface
resources or -i n for network interface resources.
By default,
the -i n flag adds network interface resources that have IPv4
addresses to communication_group. If the -6 flag is
specified, the -i n flag will add network interface resources
that have IPv6 addresses to communication_group.
If -i is
specified, -S cannot be specified.
- -S {h | n}:"network_selection_string"
- Assigns communication_group to the heartbeat or network
interface that is specified by interface_selection_string.
Specify -S h for heartbeat interfaces or -S n for network
interfaces.
By default, the -S n flag adds network interface
resources that have IPv4 addresses to communication_group.
If the -6 flag is specified, the -S n flag will add
network interface resources that have IPv6 addresses to communication_group.
If -S is
specified, -i cannot be specified.
- -6
- Specifies that IPv6 addresses represented as resources on each
interface have their communication group changed to the one specified.
IPv4 addresses represented as resources on the interfaces would be
unaffected.
By default (without -6 specified), the inverse
is true. Only IPv4 addresses represented as resources on the interface
would have their communication group changed.
- -h
- Writes the command's usage statement to standard output.
- -T
- Writes the command's trace messages to standard error. For your
software service organization's use only.
- -V
- Writes the command's verbose messages to standard output.
Parameters
- communication_group
- Specifies the name of the new communication group that is to be
created for the online peer domain. The name can contain any printable
character.
Security
The user of the mkcomg command
needs write permission for the IBM.CommunicationGroup resource
class. Write permission for the IBM.NetworkInterface resource
class is required to set the communication group for a network interface
resource. By default, root on any node in
the peer domain has read and write access to these resource classes
through the configuration resource manager.
Exit Status
- 0
- The command ran successfully.
- 1
- An error occurred with RMC.
- 2
- An error occurred with a command-line interface script.
- 3
- An incorrect flag was entered on the command line.
- 4
- An incorrect parameter was entered on the command line.
- 5
- An error occurred that was based on incorrect command-line input.
Environment Variables
- CT_CONTACT
- Determines the system where the session with the resource monitoring
and control (RMC) daemon occurs. When CT_CONTACT is set to a host
name or IP address, the command contacts the RMC daemon on the specified
host. If CT_CONTACT is not set, the command contacts the RMC daemon
on the local system where the command is being run. The target of
the RMC daemon session and the management scope determine the resource
classes or resources that are processed.
- CT_IP_AUTHENT
- When the CT_IP_AUTHENT environment variable exists, the RMC daemon
uses IP-based network authentication to contact the RMC daemon on
the system that is specified by the IP address to which the CT_CONTACT
environment variable is set. CT_IP_AUTHENT only has meaning if CT_CONTACT
is set to an IP address; it does not rely on the domain name system
(DNS) service.
Restrictions
This command must be run on
a node that is defined and online to the peer domain where the communication
group is to be defined.
Implementation Specifics
This command is
part of the Reliable Scalable Cluster Technology (RSCT) fileset
for AIX®.
Standard Input
When the -f
"-" or -F "-" flag
is specified, this command reads one or more node names from standard
input.
Standard Output
When the -h flag
is specified, this command's usage statement is written to standard
output. All verbose messages are written to standard output.
Standard Error
All trace messages are written
to standard error.
Examples
- To define the communication group ComGrp1 for
the peer domain ApplDomain and nodeA is
defined and online to ApplDomain, run this
command on nodeA:
mkcomg ComGrp1
- To define the communication group ComGrp1 for
the peer domain ApplDomain, using a sensitivity
of 1 and period of 3, and nodeA is defined
and online to ApplDomain, run this command
on nodeA:
mkcomg -s 1 -p 3 ComGrp1
- To define the communication group ComGrp1 for
the peer domain ApplDomain, not using broadcast,
using a priority of 3, and nodeA is defined
and online to ApplDomain, run this command
on nodeA:
mkcomg -x b -t 3 ComGrp1
- To define the communication group ComGrp1 for
the peer domain ApplDomain, not using broadcast,
not using source routing, and nodeA is
defined and online to ApplDomain, run the
following command on nodeA:
mkcomg -x br ComGrp1
- To define the communication group ComGrp1 for
the peer domain ApplDomain, using a NIM
path of /usr/sbin/rsct/bin/hats_nim, NIM
parameters -l 5 to set the logging level,
and nodeA is defined and online to ApplDomain,
run this command on nodeA:
mkcomg -e /usr/sbin/rsct/bin/hats_nim -m "-l 5" ComGrp1
- To define the communication group ComGrp1 for ApplDomain and
assign ComGrp1 to the heartbeat interface resource named hbi0 on nodeC,
run this command on nodeA:
mkcomg -i h:hbi0:nodeC ComGrp1
- To define the communication group ComGrp1 for
the peer domain ApplDomain, assign ComGrp1 to
the network interface resource named eth0 on nodeB,
and nodeA is defined and online to ApplDomain,
run this command on nodeA:
mkcomg -i n:eth0:nodeB ComGrp1
- To define the communication group ComGrp1 for ApplDomain and
assign ComGrp1 to the heartbeat interface resource that uses
the subnet 9.345.67.812, run this command on nodeA:
mkcomg -S h:"Subnet == 9.345.67.812" ComGrp1
- To define the communication group ComGrp1 for
the peer domain ApplDomain, assign ComGrp1 to
the network interface resource that uses the subnet 9.123.45.678,
and nodeA is defined and online to ApplDomain,
run this command on nodeA:
mkcomg -S n:"Subnet == 9.123.45.678" ComGrp1
- To define the communication group ComGrp1 for ApplDomain,
using a period of 500 milliseconds, run this command on nodeA:
mkcomg -p 0.5 ComGrp1
Location
- /usr/sbin/rsct/bin/mkcomg