Once the maximum amount of RAM that is cost effective is determined, if there is a remaining choice between speed and latency, choosing the memory with lower latency is recommended.
Given the system and processor architectures already selected, we recommend utilizing the maximum amount of RAM that can be cost effectively added to the host system. Typically, there is a price point where the cost of moving to the next DIMM size (that is, 2 GB DIMMs to 4 GB DIMMs) is more than twice the cost, and in some cases, it approaches the cost of an entire server. We recommend fully populating the server up to that price point. For example, if the server has 8 DIMM slots and 4 GB DIMMs are much more than twice the cost of 2 GB DIMMs, we recommend fully populating the server with 2 GB DIMMs and considering a second host server if additional capacity is required.
For all host server architecture, a minimum of 16 GB of RAM is recommended
Network Architecture The network architecture of the host server is a frequently overlooked topic in
host server sizing because Gigabit Ethernet NICs are now very inexpensive and most servers have at least two built in. The topic is important, however, because it is directly impacted by the host server architecture pattern selected. As mentioned previously, if an iSCSI storage architecture is being utilized, NICs will need to be dedicated to storage I/O traffic. Gigabit Ethernet is a high-speed network transport, though a host server with a large number of guests may require greater than Gigabit speed, thus requiring additional NICs. Finally, it is recommended that each host server have a NIC dedicated to the host itself for network I/O and management.
As described earlier, a fairly large number of NICs per host server may be required. This is the one factor that can mitigate against blade servers in some instances. Recently, 10-Gigabit Ethernet has become commonly available and is starting to drift lower in price, similar to the way Gigabit Ethernet has done over the years. The ability for servers to utilize 10-Gigabit Ethernet NICs is a significant factor in increasing the consolidation ratio.
Use multiple NICs and multi-port NICs on each host server.
One NIC dedicated to the host machine only for management purposes