Powering Data Centers

#redundancy #power

(OBJ 3.4)

Power Key Terms

Surges
- Sudden, small increases in voltage beyond the standard level (e.g., 120V in the US)
- Example:
  - If voltage went up to 125V or 130V instead of remaining at 120V, we would call this a slight increase in the amount of power being received as a surge.
Spikes
- Short-lived voltage increases, often caused by short circuits, tripped breakers, or lightning
- Example:
  - You might see a default voltage of 120V rise all the way up to 150V or 175V or even more.
- For protection against surges or spikes, your systems should utilize a surge protector or line conditioner which should be able to remove any power levels that are higher than about 120V.
Sags
- Brief decreases in voltage, usually not severe enough to cause system shutdown
- It could damage your hardware components over time, so you still want to use something like a line conditioner to account for this.
- Example:
  - It is common to see sags that drop the voltage from 120V to 117V or 115V instead
  - Your computers will remain online and operational because there is still enough power to run them.
Undervoltage Events (Brownouts)
- Prolonged reduction in voltage, leading to system shutdown
  - Longer period of time with voltage below default
- Example:
  - If you are expecting to receive 120V of power, but the voltage level drops down to 70V or 80V instead, this would be considered an undervoltage event.
  - Voltage will be too low for your sytems to continue to operate so they will go offline and power themselves down.
Power Loss Events (Blackouts)
- Complete loss of power for a period, potentially causing data loss and damage
- Example:
  - If the power is completely lost for a minute or two, that would be considered a complete power loss event.
- It is really important to be aware that when power is restored it can also cause a power spike to occur, which could damage your systems too.

Power Protection Components

Line Conditioners
- Stabilize voltage supply and filter out fluctuations
  - Used to overcome any minor fluctuations in the power being received by the given system
- Mitigate surges, sags, and undervoltage events
- Prevent unexpected system behavior and hardware degradation
  - Automatically adjust the power signal being received as an undervoltage or overvoltage condition and change it back to the standard power level
- Unsuitable for significant undervoltage events or complete power failures
Uninterruptible Power Supplies (UPS)
- Provide emergency power during power source failures
- Offer line conditioning functions
- Include battery backup to maintain power during short-duration failures
- Most UPS units typically supply 15 to 60 minutes of power during a complete power failure
- Really designed to prevent data loss or hardware damage during a sudden or short-duration power loss event and not going to be something that's going to help you for the long term power outages.
Generators
- Convert mechanical energy into electrical energy for use in an external circuit through the process of electromagnetic induction
- Backup generators supply power during power grid outages
- Smaller generators for limited applications (e.g., emergency lighting)
- Different Types of Generators
  - Portable gas-engine generators
    - Least expensive, because it usually uses just a small gasoline engine to convert mechanical motion into electrical power.
    - Tend to be smaller and more portable, but they also can't support providing high levels of poser either so they can't be used to power an entire building.
    - They tend to be very noisy when they're operating because of the gas-engine.
    - Means higher levels of maintenance because of gas-based engine.
    - Not suitable for a large server room, but you may be able to keep some specialized equipment up and running, using one of these portable systems.
    - Can be run for either a short or long period of time depending on the amount of fuel you have available.
  - Permanently installed generators
    - Make up the backbone of your data center's emergency power architecture.
    - Rely on either diesel fuel, propane, or other types of natural gas to operate, and tend to be very large
    - They can power an entire building during a complete power loss event for hours, days, or even weeks depending on how much fuel is available.
    - Directly integrated into the data center's electrical setup and they're designed to kick in automatically during a power loss event.
  - Battery-inverter generators
    - Rely on large lead-acid batteries, nickel-cadmium batteries, or lithium-ion batteries.
    - Tend to be quiter and require less maintenance than either the portable gas engine generator or the permanently installed generator.
    - Unfortunately, most of them can only provide minimum wattage or provide power for a short duration of time during an outage so they aren't really designed for prolonged use.
    - Useful for bridging the gap until a longer-term backup solution, like a diesel generator, propane generator, or natural gas generator, can be brought online and take over our power supply needs.
Power Distribution Centers (PDC)
- Central hub for power reception and distribution to all systems in the data center
- Includes circuit protection, monitoring, and load balancing to ensure even distribution without overloading any of your circuits.
  - "Not just a big power strip"
- Integrates with UPS and backup generators for seamless transitions during power events.

Considerations for Data Centers

Large data centers use rack-mounted UPS for server protection
UPS provides line conditioning and battery backup for 10-15 minutes
Power distribution units manage load balancing and line conditioning to each server rack from your main utility power source.
- They can also receive their power from backup generators if your grid power is lost or unavailable.
Backup generators are crucial for extended power outages but require startup time
- Note generators usually take about 30 to 60 seconds for them to start up, and then once they come up to speed, they'll be ready to start carrying the power load that you need to your power distribution centers.
Building data centers with redundancy and protections tailored to use cases and budgets