By default running your Exalogic in a Virtual provides you with,
what to Cloud Users, is a single large resource and they can just
create vServers and not care about how they are laid down on the
the underlying infrastructure. All the Cloud Users will know is
that they can create vServers. For example if we have a Quarter
Rack (8 Nodes) and our Cloud User creates 8 vServers those 8
vServers may run on 8 distinct nodes or may all run on the same
node.
Although in many cases we, as Cloud Users, may not be to worried
how the Virtualisation Algorithm decides where to place our
vServers there are cases where it is extremely important that
vServers run on distinct physical compute nodes. For example if we
have a Weblogic Cluster we will want the Servers with in the
cluster to run on distinct physical node to cover for the
situation where one physical node is lost.
To achieve this the Exalogic Virtualised implementation provides
Distribution Groups that define and anti-aliasing policy that the
underlying Virtualisation Algorithm will take into account when
placing vServers.
It should be noted that Distribution Groups must be created
before you create vServers because a vServer can only be added to
a Distribution Group at creation time.
Creating A Distribution Group
To create a Distribution
Groups we will first need to select the Account in which we want
the Distribution Group to be created. Once we have selected the
account we will see the Interface update and Account specific
Actions will be displayed within the Action Panes. From the Action
pane (or Right-Click on the Account) select the "Create
Distribution Group" action.
This will initiate the create wizard as follows.
Distribution Group Details
Within the first Step of the Wizard we can specify the name of
the distribution group and this should be unique. In addition we
can provide a detailed description of the group.
Distribution Group Configuration
The second step of the configuration wizard allows you to specify
the number of elements that are required within this group and
will specify a maximum of the number of nodes within you Exalogic.
At this point it is always better to specify a group with spare
capacity allowing for future expansion. As vServers are added to
group the available slots decrease.
Summary
Finally the last step of the wizard display a summary of the
information entered.
