Price

One often cited reason for wanting to go with large dense nodes is to try and drive down the cost of the hardware purchase. This is often a false economy as dense nodes tend to require premium parts that often end up costing more per GB than less dense nodes.

For example, a 12 disk node may only require a single quad processor to provide enough CPU resource for OSDs. A 60 bay enclosure may require dual 10 core processors or greater, which are a lot more expensive per GHz provided. You may also need larger Dual In-line Memory Modules (DIMMs), which demand a premium and perhaps even increased numbers of 10G or even 40G NICs.

The bulk of the cost of the hardware will be made up of the CPUs, memory, networking, and disks. As we have seen, all of these hardware resource requirements scale linearly with the number and size of disks. The only area that larger nodes may have an advantage in is requiring fewer motherboards and power supplies, which is not a large part of the overall cost.