Small server room: rack, cooling and UPS according to industry standards

Even if you have moved many workloads to Azure, most companies still need a small local server room — for NAS, telephony, domain controllers, video surveillance, and print servers. Good room design is the difference between a decade of peace and a series of late-night calls.

TL;DR — key points

• For a typical SMB, a 12–22U wall-mounted or floor-standing rack is sufficient
• Cooling for an average business rack is ~500–2000 W of heat — a dedicated split air conditioner is required
• UPS should last at least 10 minutes at full load — enough for a safe shutdown
• Temperature, humidity and voltage monitoring is inexpensive and prevents damage

Plan and location

The ideal room is on the ground floor or basement, without direct sunlight, far enough from water pipes, sewage pipes and boiler rooms. We recommend a separate room with a burglar-proof door, no windows (or with flood protection), its own electrical circuit and a dedicated grounding lead.

Rack — what to get and where

• Wall-mounted rack (6–12U) for smaller environments with 1–2 devices and a switch
• Floor-standing rack (22–42U) for multiple servers, several UPS units and structured cabling
• Depth at least 800 mm for modern server equipment (Dell, HPE, Lenovo)
• Load capacity at least 600 kg for a typical 22U rack
• Feet or casters, separate rear door, cable management channels

Power supply and UPS

Every device in the rack should be connected to a UPS. Basic choices:

The UPS should be connected to a monitoring system (SNMP or USB) so that servers automatically shut down safely during a prolonged outage. Replace batteries every 3–5 years, do not wait for them to fail.

Cooling

A rack with 2 servers emits 500–1200 W of heat, which can quickly raise the temperature in a small room by several degrees. We recommend:

• Dedicated split air conditioning system (do not use office AC that shuts off at night)
• Redundant cooling or at least a backup portable AC unit in case of failure
• Humidity control — we recommend 40–60% RH
• Hot/cold aisle concept if you have multiple racks

Environmental monitoring

An inexpensive sensor (Netio, HWg-STE, APC NetBotz) sends you an alarm when:

• Temperature exceeds 27 °C
• Humidity falls below 30% or rises above 65%
• Smoke or water on the floor is detected
• UPS switches to battery power
• Any of the devices turn off

Alarms should go to a Teams channel or the technician's email. Early warning is the only thing that prevents major damage.

Cabling and documentation

Use color-coded cables (red = LAN, blue = management, yellow = WAN, gray = uplink), neat cable channels and labels on both ends. Document every port in a simple table (Excel or NetBox). When something "stopped working", 80% of the solution is proper documentation.

Fire and physical security

• Manual fire extinguisher (CO₂ or clean agent) suitable for electronics
• Smoke detector connected to the company's alarm center
• Access control — doors with electronic locks and access logs
• Video surveillance of the entrance

When to consider colocation or the cloud

If a renovation or relocation occurs, or if you cannot provide cooling and power redundancy, consider colocation (renting a rack in a data center) or moving workloads to Azure. Data centers in Slovenia offer a professional environment at affordable prices — often cheaper than your own investment in a room renovation.

Do I need redundant power with two circuits?

For an SMB with one rack, usually not — a quality UPS and a building-level generator are enough. Redundancy with two physical power paths makes sense when the load exceeds 5 kW or high availability is required.

What temperature should I maintain in the room?

We recommend 20–24 °C. Lower temperatures do not bring extra reliability but do result in significantly higher cooling costs.

How often should I test the UPS and fire extinguisher?

UPS: automatic test once a month, manual battery test once a year. Fire extinguisher: legal inspection once a year.

Do I need a generator?

For an SMB with one rack, it is not mandatory if you have cloud backup and can work remotely during a prolonged outage. For key operational premises (manufacturing, call centers), a generator is a sensible investment.