Compatibility with physical infrastructure

Decades ago, computers were large and standards were few; each might demand a dedicated room with unique physical requirements. These days, we enjoy considerable benefits from standards and convergent designs, yet there can still be surprises. Just within the preceding five years this author has encountered the following:

• Serial console infrastructure defaulting to 9,600 bps but equipment defaulting to 19,200 bps
• Atypical DTE/DCE pinouts incompatible with common RJ45 adapters
• Gear that still uses 1990s-style DB9 connectors or even an audio-type 3.5mm round jack for management access
• One server model out of a larger product line with an unusual onboard network interface whose PXE code for network boots would inexplicably switch the system's serial console to 115,200 bps.
• A server vendor whose mounting hardware was designed for 19" racks with square holes. These rails, in theory, were usable with common round hole racks, yet had to be attacked with a power drill due to differing hole/screw sizes.

Chances are that you are well versed in your local server practices, but these are among the gotchas that can still arise when considering new brands or product generations.

Take care as well that your server choices will fit into your data center racks! Some very dense servers, such as 90-drive 4U beasts, can be so deep that they do not fit well into racks, and may block aisles or prevent doors from closing. Gather your dimensional constraints in advance and pay careful attention to spec tables.