Database Reference
In-Depth Information
ODA Node
#1
ODA Node
#2
User VM
User VM
DOM
0
DOM
0
ODA_BASE
ODA_BASE
Figure 10-1.
Basic architecture of a virtualized ODA
Domain 0, or Dom0, is the virtualization controller, which is a dummy operating system that has access to a
hypervisor for the virtualized box. There is a Dom0 in both physical nodes; it is considered the piece that manages the
visualized infrastructure of the ODA. Dom0 is used as the base operating system, and as such, nothing else should be
installed on it. Dom0 does host the virtual template repository, however, and as such, all VM templates are imported
from there.
The Database VM, also known as ODA_BASE, is a critical aspect of the appliance. ODA_BASE is a specially
designed VM that has direct access to part of the ODA hardware. It has various drivers optimized for the ODA
hardware that are already installed and configured for improved access to the hypervisor and the shared disks.
The ODA_BASE template includes the cluster software binaries, database software binaries, as well as the custom
database templates that are needed to create an Oracle database.
The other aspect of virtualization is installing an application or any other components in a separate visualized
host. This is what is called a User VM. User VMs are not mandatory and an ODA can be virtualized and contain only
a Dom0 and an ODA_BASE. Currently, there are space limitations on User VMs unless a shared VM repository is
used. Shared repository support is a new feature in ODA 2.8, but prior to that, only 250GB was available on the ODA
V1, and 350GB on the ODA X3-2 in local disk space on each physical machine. Also, User VMs did not have failover
capabilities in previous releases of the ODA software.
Virtualization Deployment Considerations
It is very important to understand the changes in the ODA deployment strategy when used as a virtualized
environment. Sizing and network changes need to be understood for the deployment. The appliance does not ship
with virtualization installed unless an independent software vendor (ISV) creates a custom appliance that ships with
virtualization enabled.
Table
10-1
and Table
10-2
look at the differences between the ODA V1 and the ODA X3-2 in terms of bare metal
vs. virtualized interfaces. In a bare-metal environment, all network interfaces have a physical mapping and there
is bonding at the Linux layer to provide High Availability to the network interfaces. It is very important to adhere to
documentation and ensure that Eth0 is only used for the private interfaces.
