The workload manager (WLM) shall be implemented on all AIX systems. On most systems WLM will be running in "passive" mode, which does not limit resources. In MtXia's environment, only a few selected systems will have WLM implemented in "active" mode to control and regulate resources. If there is any question as to whether WLM should be implemented in "active" or "passive" mode, default to "passive".
The WLM provides a mechanism to classify and segment resources by process, user, group, etc. The classification scheme must be constructed by the AIX system administrator. This WLM classification scheme in the MtXia environment is based on the concept of the Resource Group. Each Resource Group will be represented in WLM as a class. Multiple instances of an application within a single resource group shall be represented in WLM as subclasses.
In order to configure WLM, the system administrator must first define the resource groups names. Once the resource group names have been defined, then a WLM class must be defined using the resource group name as the WLM class name.
To define a new WLM class using smitty, start smitty using the "wlm" fastpath.
smitty wlm
Select "Add a class" to define a new WLM class.
Workload Management
Move cursor to desired item and press Enter.
List all Classes
Add a Class
Change / Show Characteristics of a Class
Remove a Class
Class Assignment Rules
Start/Stop/Update WLM
Enter the resource group name as the WLM class name, and provide a description of this WLM class. The Tier level will normally be 0 (zero) unless there is a specific reason to change this. The CPU and Memory values will be defaulted to a minumum of 0% and a maximum value of 100%.
Add a Class
Type or select values in entry fields.
Press Enter AFTER making all desired changes.
[Entry Fields]
Class name [atladtu1]
Description [Atlas pre-prod Database for Mt Xia, instance 1]
Tier [0]
Minimum CPU time (%) [0]
Maximum CPU time (%) [100]
Shares of CPU [1]
Minimum Memory (%) [0]
Maximum Memory (%) [100]
Shares of Memory [1]
Class rules are used to determine which processes are assigned to which WLM classes and the order of the rules is significant. The first rule that matches is used to determine the WLM class assignment, so the class rules should be ordered from highly specific to less specific.
To define WLM class rules using smitty, start smitty using the "wlm" fastpath.
smitty wlm
Select "Class assignment rules" to define a new WLM class.
Workload Management
Move cursor to desired item and press Enter.
List all Classes
Add a Class
Change / Show Characteristics of a Class
Remove a Class
Class Assignment Rules
Start/Stop/Update WLM
Select "Class assignment rules" to define a new WLM class rule.
Class Assignment Rules
Move cursor to desired item and press Enter.
List all Rules
Create a new Rule
Change / Show Characteristics of a Rule
Delete a Rule
In the following example, a rule is defined to assign all processes owned by oracl817 to the the WLM class "atladtu1". Again the order of the rules is important. The rules should be ranked in order of highly specific, starting at 1, to less specific.
Create a new Rule
Type or select values in entry fields.
Press Enter AFTER making all desired changes.
[Entry Fields]
* Order of the Rule [1]
* Class [atladtu1]
User [oracl817]
Group [-]
Application [-]
Under AIX 4.3.3.0, to start WLM in passive mode, it must be done from the command line. If WLM is started from "smitty", it will be started in "active" mode. So to be safe and exact, always start/stop WLM from the command line using the appropriate flags.
To start WLM from the command line in "passive" mode:
wlmcntrl -p
To start WLM from the command line in "active" mode:
wlmcntrl -a
To stop WLM from the command:
wlmcntrl -o
Any changes to the WLM configuration will require that WLM be stopped and restarted in order for the changes to take effect.
An example WLM configuration of the Atlas pre-production Database server for Mt Xia follows. The "standard" WLM configuration for this machine contains five WLM classes. It is important to recognize that the "standard" WLM configuration will be different for every machine. The term "standard" is used in reference to the local machine, this is not enterprise wide terminology used here.
The AIX 4.3.3.0 WLM does not support the concept of subclasses, therefore multiple instances of an application will likely be configured as multiple WLM classes, requiring multiple resource groups. Since the AIX 4.3.3.0 WLM does not support subclasses, the WLM configuration will be different between AIX 4.3.3.0 and AIX 5.X systems.
System:
Default:
atladtu1:
description = "Atlas pre-prod Database for Mt Xia, AMST instance"
atladtu2:
description = "Atlas pre-prod Database for Mt Xia, C2KR instance"
atladtu3:
description = "Atlas pre-prod Database for Mt Xia, ATLP instance"
The class rules associated with this "standard" configuration assign processes to multiple classes depending upon the user id. Rules are defined to segment the processes owned by the three oracle instances into separate WLM classes. All processes owned by "root" are assigned to the class "System", and all other processes are assigned to the class "Default".
* class resvd user group application
atladtu1 - oracl817 - -
atladtu2 - oracle8i - -
atladtu3 - oracle - -
System - root - -
Default - - - -