mkcomg Command

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

1. 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

2. 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

3. 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

4. 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

5. To define the communication group ComGrp1 for the peer domain ApplDomain, using a NIM path of /opt/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 /opt/rsct/bin/hats_nim -m "-l 5" ComGrp1

6. 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

7. 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

8. 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

9. 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

10. 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

/opt/rsct/bin/mkcomg