Creating Hostgroups For X9000 Clients; How Hostgroups Work; Creating A Hostgroup Tree - HP StorageWorks x9300 Administrator's Manual

7 Creating hostgroups for X9000 clients

A hostgroup is a named set of X9000 clients. Hostgroups provide a convenient way to centrally
manage clients using the management console. You can put different sets of clients into hostgroups
and then perform the following operations on all members of the group:
Create and delete mountpoints
Mount file systems
Prefer a network interface
Tune host parameters
Set allocation policies
Hostgroups are optional. If you do not choose to set them up, you can mount file systems on clients
and tune host settings and allocation policies on an individual level.

How hostgroups work

In the simplest case, the hostgroups functionality allows you to perform an allowed operation on
all X9000 clients by executing a management console command on the default clients hostgroup
via either the CLI or the GUI. The clients hostgroup includes all X9000 clients configured in the
cluster.
NOTE: The command intention is stored on the management console until the next time the clients
contact the management console. (To force this contact, restart X9000 Software services on the
clients, reboot them, or execute ibrix_lwmount -a or ibrix_lwhost --a.) When contacted,
the management console informs the clients about commands that were executed on hostgroups
to which they belong. The clients then use this information to perform the operation.
You can also use hostgroups to perform different operations on different sets of clients. To do this,
you will need to create a hostgroup tree that includes the necessary hostgroups. You can then
assign the clients manually, or the management console can automatically perform the assignment
when you register an X9000 client, based on the client's cluster subnet. To use automatic assignment,
you will need to create a domain rule that specifies the cluster subnet for the hostgroup.

Creating a hostgroup tree

The clients hostgroup is the root element of the hostgroup tree. Each hostgroup in a tree can
have exactly one parent, and a parent can have multiple children, as shown in the following
diagram). In a hostgroup tree, operations performed on lower-level nodes take precedence over
operations performed on higher-level nodes. This means that you can effectively establish global
client settings that you can override for specific clients.
For example, suppose that you want all clients to be able to mount file system ifs1 and to
implement a set of host tunings denoted as Tuning 1, but you want to override these global settings
for certain hostgroups. To do this, mount ifs1 on the clients hostgroup, ifs2 on hostgroup
A, ifs3 on hostgroup C, and ifs4 on hostgroup D, in any order. Then, set Tuning 1 on the
clients hostgroup and Tuning 2 on hostgroup B. The end result is that all clients in hostgroup B
will mount ifs1 and implement Tuning 2. The clients in hostgroup A will mount ifs2 and implement
Tuning 1. The clients in hostgroups C and D respectively, will mount ifs3 and ifs4 and implement
Tuning 1.
The following diagram shows an example of global and local settings in a hostgroup tree.
44 Creating hostgroups for X9000 clients