A folder is a container for BIG-IP® configuration objects and files on a BIG-IP device. Virtual servers, pools, and self IP addresses are examples of objects that reside in folders on the system.
In the context of the BIG-IP system, a folder is a container for BIG-IP system objects. Folders resemble standard UNIX directories, in that the system includes a hierarchy of folders and includes a root folder (represented by the / symbol) that is the parent for all other folders on the system.
You can create sub-folders within a high-level folder. For example, if you have a high-level folder (partition) within the root folder named Customer1, you can create a sub-folder, such as App_B, within Customer1.
A folder can contain other folders.
One of the important ways that you can use folders is to set up full or granular synchronization and failover of BIG-IP configuration data in a device group. You can synchronize and fail over all configuration data on a BIG-IP device, or you can synchronize and fail over objects within a specific folder only.
You manage BIG-IP folders and sub-folders using the Traffic Management Shell (tmsh) command line interface.
Folders have two specific redundancy attributes that enable granular synchronization and failover of BIG-IP® system data within a device group. These two attributes are a device group name and a traffic group name.
This attribute determines the scope of the synchronization, that is, the specific devices to which the system synchronizes the contents of the associated folder. When you create a Sync-Failover device group on a BIG-IP device, the system assigns that device group name as an attribute of folder root. Any other folders that you subsequently create on a device group member then inherit that same device group name, by default.
The result is that when you enable config sync for the local device, the contents of the root folder and any sub-folders are synchronized across the members of the specified device group.
This attribute determines the scope of a failover action, that is, the specific configuration objects that will fail over if the device becomes unavailable. If you enabled failover on a device (as part of running the Setup utility or upgrading from a previous BIG-IP version), the device contains the default traffic group named traffic-group-1. The system assigns this traffic group name by default as an attribute of folder root. Any other folders that you subsequently create on a device group member inherit that same traffic group name, by default. The result is that when the local device is a member of a Sync-Failover device group, all failover objects within the root folder and its hierarchy fail over based on the definition of the specified traffic group.
You can assign a different traffic group to a specific sub folder. For example, you can create an iApps™ application in a sub folder and change the inherited traffic group value of traffic-group-1 to a traffic group that you create, such as traffic-group-2. You can then manually cause traffic-group-2 to fail over to another device so that the iApp application runs on a separate device from traffic-group-1.
At the highest-level, the BIG-IP® system includes a root folder. The root folder contains all BIG-IP configuration objects on the system, by way of a hierarchical folder and sub-folder structure within it.
By default, the BIG-IP system assigns a Sync-Failover device group and a traffic group to the root folder. All folders and sub-folders under the root folder inherit these default assignments.
An HA score is a numeric value that the BIG-IP® system calculates independently for each instance of a particular traffic group, when you have assigned an HA group to each traffic group instance. For each traffic group instance, the HA group's monitoring function determines the availability of certain resources such as trunk links, pool members, or VIPRION® cluster members.
The BIG-IP system uses these per-instance scores to decide which device has the most resources that the traffic group needs, such as trunk links or pool members. The higher the score for a traffic group instance, the higher the availability of needed resources.
You must have an HA group assigned to each instance of the same traffic group in order for the system to calculate an HA score. An HA score is calculated based on how the corresponding HA group is configured. Whenever the HA group for the active traffic group decides to trigger failover, the traffic group automatically fails over to the device with the highest score.
To get the BIG-IP to base the selection of a traffic group's next-active device on an HA score, you configure the Failover to Device with Best HA Score Failover Method setting on a floating traffic group.