Standard Rack Mounted Servers The most common system architecture is a standard rack mounted server.
Typically found in 2U or 4U models, these servers typically contain 2 to 4 CPU sockets, 2 to 8 PCI-E or PCI-X slots, and 4 to 6 hard disk bays. Rack mounted servers are excellent choices for Hyper-V hosts due the low cost of commodity 2- and 4-socket servers and their inherent scalability and expandability through additional NIC and HBA slots.
Rack mounted Intel- or AMD-based servers are recommended for any of the host server architecture patterns.
Blade Servers Blade servers have dramatically increased in popularity and capability due to the
ever increasing need for capacity and server density. Blade server architectures are a primary area of R&D for the server manufacturers, resulting in a significant amount of innovation in this space. The downside of blade servers is limited standards and interoperability between manufacturers and, in some cases, within the same manufacturer when they change their blade chassis architecture.
The processor and space density benefits of blade servers initially came at the expense of expandability and the quantity of NICs and HBAs that can be supported in the first several generations of blade servers.
Recently, the advent of blade architectures where each blade contains 8 to 16 cores, up to 64 GB of RAM, and most importantly, 6 or more IO interfaces has eliminated many disadvantages that previously mitigated against using blade server architectures for virtualization.
The network and storage I/O that is required to support the desired number of guests on each host server must be considered carefully to ensure that each host server is running on a blade and the blade chassis itself can support it.
The host server architecture must be considered when evaluating blade server system architectures. If an iSCSI storage system is planned, two additional dedicated NICs are required for access to the storage and redundancy. Finally, at least two NICs should be dedicated to network I/O. The number of NICs required per host can easily expand from 4 to 6 or more NICs. This is frequently beyond the number supported by many blade servers.