What's the Difference Between Passive RFID and Active RFID for Data Center Asset Management?

Passive RFID (Radio Frequency Identification) and Active RFID are two different technologies used in Asset Management to track and identify assets in a data center, but only one is automated and real time.

Passive RFID and active RFID have distinct characteristics that determine the amount of benefit they can provide for data center asset management.  The characteristics below are described for use in a data center environment which is different to other environments because of dense concrete, metal and other signals.

Passive RFID Characteristics:

1. No internal power source: The passive RFID tag does not have a built-in battery or power source and needs to be powered temporarily by an external device.
2. Transmits only when activated: Passive RFID tags only send a signal when they are activated manually with a reader device, which powers the tag temporarily.  All other times the tag is inactive.
3. Limited read range: Typically a person needs to be in close proximity to the passive RFID tag in order to locate and identify a specific asset. Up to 24 inches (0.6m), depending on the frequency band used.
4. Low read volume: Passive RFID is typically only useful for reading one passive tag per person at a time.
5. Location data ages quickly: Data is only accurate for the last time the passive tag was manually scanned.  Frequent manual scans are required to keep data accurate.
6. Low cost per tag: Tags are relatively inexpensive.

Active RFID Characteristics:

1. Internal power source: The active RFID tag has a built-in battery that powers the tag's transmitter.
2. Transmits continuously or at regular intervals: Unlike passive tags, active RFID tags transmit their ID and location information on a regular basis, without needing external activation.
3. Long read range: Up to 300 feet (91m).  An important difference is that because active RFID tracks all assets in real time an asset can be located and identified without requiring a person to visit the data center.
4. Very high read volume: With active RFID up 1,400 asset tags can be read simultaneously per reader automatically.
   
5. Continuous real-time location system (RTLS) and asset tracking: Active RFID operates continuously to keep data accurate.  The age of location data is typically +- 2 minutes.
   
6. Higher cost per tag: Because of the enhanced technology compared to passive tags, active RFID tags can cost more per tag than passive RFID tags. Active RFID tags provide a higher return for the investment than passive RFID.

Passive RFID Suitability:

Passive RFID for data center asset management is more suitable for:

1. Low-volume asset tracking.
2. Supporting or augmenting, but not eliminating, manual process.
3. An alternative to bar codes and bar code scanners.
4. When asset audits and accuracy for internal or external compliance are not required.

Active RFID Suitability:

Active RFID for data center asset management is more suitable for:

1. High-volume asset tracking.
2. Eliminating and automating manual process, e.g. for automated and continual asset audits.
3. When high-frequency updates are necessary for inventory management or other purposes.
4. When asset audits and accuracy for internal or external compliance are required.
   

Real World Experience

Learning from the experience of others who have used a solution is a great way to better understand what solution is suitable for you and your situation.  You can find some case studies from real world use of RFID solutions here.