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Logical Volume Group (LVG) Management Overview

LVG Overview​

LVG refers to the Logical Volume Group management module in the ansible-power-aix repository. It is used to create, remove, modify attributes, resize, activate, and deactivate volume groups on AIX systems. The module supports various actions such as creating a volume group, extending it by adding physical volumes, and removing physical volumes from it. It also allows for setting specific attributes like the type of volume group, enabling enhanced concurrent capabilities, and specifying critical physical volumes.

Usage of LVG​

The LVG module is used in various scenarios such as creating a scalable volume group with a mirror pool, creating a volume group with multiple physical volumes, extending a volume group, removing a volume group, and varying on or off a volume group. This section provides examples of how to use the LVG module for different operations like creating, extending, and removing volume groups.

Examples of using the LVG module to create, extend, and remove volume groups.

- name: Create a scalable volume group with a mirror pool
  ibm.power_aix.lvg:
    state: present
    vg_name: datavg
    pvs: hdisk1
    vg_type: scalable
    mirror_pool: mp1

- name: Create a volume group with multiple physical volumes
  ibm.power_aix.lvg:
    state: present
    vg_name: datavg
    pvs: hdisk1 hdisk2 hdisk3

- name: Extend a volume group
  ibm.power_aix.lvg:
    state: present
    vg_name: datavg
    pvs: hdisk1

- name: Remove a volume group

Main Functions​

There are several main functions in this folder. Some of them are make_vg, extend_vg, change_vg, reduce_vg, and vary_vg. We will dive a little into make_vg and extend_vg.

make_vg​

The make_vg function is responsible for creating a volume group. It constructs the necessary command options and executes the command to create the volume group.

The make_vg function constructs the necessary command options and executes the command to create the volume group.

def make_vg(module, vg_name):
    """
    Creates volume group
    arguments:
        module:     Ansible module argument spec.
        vg_name:    Volume group name
    note:
        Exits with fail_json in case of error
    return:
        none
    """

    pvs = module.params['pvs']
    opt = build_vg_opts(module)

    vg_type_opt = {
        "none": '',
        "big": '-B ',
        "scalable": '-S ',
    }
    vg_type = module.params["vg_type"]

extend_vg​

The extend_vg function extends an existing volume group by adding physical volumes to it. It ensures the volume group is active before performing the extension.

The extend_vg function ensures the volume group is active before performing the extension.

def extend_vg(module, vg_name, vg_state, init_props):
    """
    Extends a varied on volume group
    arguments:
        module:     Ansible module argument spec.
        vg_name:    Volume group name
        vg_state:   Volume group state
        init_props: Initial properties of the volume group
    note:
        Exits with fail_json in case of error
    return:
        none
    """

    # fail extendvg if vg is varied off
    varied_on = vg_state
    if not varied_on:
        result['rc'] = 1
        result['msg'] = f"Unable to extend volume group { vg_name } because it is not varied on."
        module.fail_json(**result)

change_vg​

The change_vg function modifies the attributes of an existing volume group. It builds the necessary command options and executes the command to change the volume group.

reduce_vg​

The reduce_vg function reduces a volume group by removing physical volumes from it. It checks the current state of the volume group and ensures it is active before performing the reduction.

The reduce_vg function checks the current state of the volume group and ensures it is active before performing the reduction.

def reduce_vg(module, vg_name, vg_state):
    """
    Reduce volume group
    arguments:
        module: Ansible module argument spec.
        vg_name: Volume group name
        vg_state: Volume group state
    note:
        Exits with fail_json in case of error
    return:
        none
    """

    pvs = module.params['pvs']

    if vg_state is False:
        result['msg'] = f"Volume group {vg_name} is deactivated. Unable to reduce volume group."
        module.fail_json(**result)

    elif vg_state is None:
        result['msg'] = f"Volume group {vg_name} does not exist. Unable to reduce volume group."

The vary_vg function checks the current state of the volume group and executes the appropriate command to varyon or varyoff the volume group.

def vary_vg(module, state, vg_name, vg_state):
    """
    Varyon/off volume group
    arguments:
        module: Ansible module argument spec.
        state: requested action, can be varyon or varyoff
        vg_name: Volume group name
        vg_state: Volume group state
    note:
        Exits with fail_json in case of error
    return:
        none
    """

    if vg_state is None:
        result['msg'] = f"Volume group {vg_name} does not exist."
        module.fail_json(**result)

    if state == 'varyon':
        if vg_state is True:
            result['msg'] += f"Volume group {vg_name} is already active. "

 

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