cthatstune Command

Purpose

Views and changes the topology services subsystem's tunable parameters at run time.

Syntax

cthatstune [ -f [network1]:frequency1[,[network2]:frequency2…] ] [ -g [[network]:grace] ] [ -s [network1]:sensitivity1[,[network2]:sensitivity2…] ] [-p priority] [-l log_length] [-m pin_object] [-r] [-v] [-h]

Description

The cthatstune command changes the topology services subsystem's tunable parameters at run time. The topology services subsystem has two types of tunable parameters:

subsystem-wide

Affects the behavior of the topology services subsystem. This type includes the fixed priority level, the maximum length of the log file, and the object to be pinned in main memory.

per-network

Affects the behavior of each network. This type includes the heartbeat frequency and sensitivity.

The cthatstune command changes the parameters in the cluster data. The new values will not take effect until the topology services daemon reads in the new values from the cluster data. You can use a refresh operation to instruct the topology services daemon to read the new values from the cluster data. You can start a refresh operation by issuing the cthatsctrl -r command or the cthatstune -r command on one of the nodes in the cluster.

In addition to the real values, two special values: VIEW and DEFAULT, can be used to display the current setting and to use the default value of the tunable parameter, respectively.

For per-network tunable parameters, in addition to the network name, an empty network name or the special network name ALL can be used to specify that the value following the network name applies to all networks.

Flags

-f [network1]:frequency1[,[network2]:frequency2…]

Specifies the heartbeat frequency, which is the interval in seconds between heartbeats, for one or more networks.

The value of frequency can be an integer from 1 to 30. The default value is 1.

-g [[network]: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 value.

-s [network1]:sensitivity1[,[network2]:sensitivity2…]

Specifies the maximum number of missing heartbeats for one or more networks. If this maximum is exceeded, the topology services daemon considers the peer to be inactive.

The value of sensitivity can be any integer from 4 to 40. The default value is 4.

-p priority

Specifies the fixed priority level. The value of priority can be 0, which means do not run in fixed priority level, or an integer from 1 to 80. The default value is 30.

-l log_length

Specifies the maximum log file length (in number of lines). The value of log_length can be any integer from 2000 to 1 000 000. The default value is 5000.

-m pin_object [,pin_object...]

Specifies the object to be pinned in main memory. Valid values are:

NONE: Does not pin any object in main memory.
TEXT: Specifies the TEXT object to be pinned in main memory.
DATA: Specifies the DATA object to be pinned in main memory.
STACK: Specifies the STACK object to be pinned in main memory.
PROC: Specifies that all pinnable objects should be pinned in main memory. This is the default value.

-r

Applies the new tunables and refreshes the topology services subsystem.

-v

Provides verbose output.

-h

Writes the command's usage statement to standard output.

Security

You must have root authority to run this command.

Exit Status

0: Indicates that the command completed successfully.
a non-zero value: Indicates that an error occurred.

Restrictions

This command is valid in a peer domain only.

Implementation Specifics

This command is part of the Reliable Scalable Cluster Technology (RSCT) fileset for AIX®.

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

This command writes any error messages to standard error.

Examples

To change the fixed priority level to 40, view the current setting of the maximum log file length, and pin default objects in main memory, without making the new setting take effect immediately, enter:
```
cthatstune -p 40 -l VIEW -m DEFAULT
```
To make the new setting (previously changed by cthatstune) take effect, enter:
```
cthatstune -r
```
To change the fixed priority level to normal, pin program and data segments in main memory, and make the new settings take effect immediately, enter:
```
cthatstune -p 0 -m TEXT,DATA -r
```
To change the heartbeat frequency of filesys_net to 2 and all other networks to 4, change the sensitivity of all other networks to the default value, and make the new settings take effect immediately, enter:
```
cthatstune -f filesys_net:2,:4 -s :DEFAULT -r
```
To change the heartbeat frequency of filesys_net to the default value and service_net to 3, change the sensitivity of all networks to 8, pin the entire topology services subsystem in main memory, and make the new settings take effect immediately, enter:
```
cthatstune -f filesys_net:DEFAULT,service_net:3 -s :8 -m PROC -r
```
You can also do this using the following method:
```
cthatstune -f filesys_net:DEFAULT,service_net:3
cthatstune -s :8
cthatstune -m PROC
cthatstune -r
```
To change the period for network communication group CG3 to 2345 milliseconds, enter:
```
cthatstune -f CG3:2.345
```
To change the grace period for network communication group CG3 to 30500 milliseconds, enter:
```
cthatstune -g CG3:30.5
```

Location

/opt/rsct/bin/cthatstune: Contains the cthatstune command