Loading a PDW Region in APS - SQL Server Integration Services Design Patterns - page 232

• Two redundant InfiniBand switches
• Two redundant Ethernet switches
• Scale units of either two or three Compute nodes
The expansion rack is very similar to the base rack. Just like the base rack, the bot-
tom of the expansion rack includes servers and storage in scale units of either two or
three Compute nodes. In fact, the only difference between the base rack and the expan-
sion rack is the absence of the active server and optional spare server at the top of the
rack.
Software Architecture
In the previous section, we discussed that the primary difference between the base rack
and the expansion rack is the active server at the top of the rack. Let's dig into that
server in a little more detail.
The active server is comprised of four virtual machines (VMs) that provide func-
tionality essential to the operation of the appliance. The four VMs are the PDW Con-
trol node (CTL), the Management and Active Directory (MAD), the Fabric Active Dir-
ectory (AD), and Hyper-V Virtual Machine Manager (VMM). As an ETL developer or
data integration engineer, you will only interact directly with the PDW Control node
VM. Figure 8-1 depicts a nine-node rack and the four VMs that reside in the Active
Server.