Greening the Internet with Nano Data Centers

The paper provides the idea of Nano Data Centers against the traditional data center paradigm to address and improve the energy efficiency.

Data Center Limitations

1.      Overprovisioning to match the peak load demand even though average load remains much lower. Datacenters are overprovisioned because of the redundancy requirements (robustness)

2.     High cost incurred because of Heat dissipation- Heat dissipation accounts for at least 20% to 50% of total power consumption.

3.     Because of need to locate the data centers in different geographical locations, it results increased distance to end-users, which increases bandwidth mileage requirements. And, also adds to the energy consumption of networking equipment.

What is Nano Data Center or NaDa?

NaDa is a distributed service platform based on the tiny managed servers located at the edges of the network. NaDa is based on P2P protocol, with one main difference. NaDa is coordinated and managed by a single entity ISP.

Main contributions of the paper

1.      Develop model to evaluate energy consumption of Data Centers vs NaDa.

2.     Apply model in the context of video-on-demand services.

3.     Use trace-driven simulation to quantify energy savings.

Nano Data Center philosophy

1.      Take advantage of the always on gateways to achieve energy efficiency.

2.     Add memory and stronger CPU to home gateways.

3.     Push content to the gateways when bandwidth requirement is low

4.     Millions of gateways are managed as a ‘single logical unit’ using P2P infrastructure. 

Advantages of NaDa

1.      Improved Power Usage efficiency when compared to centralized data centers.

Power Usage efficiency is ratio between total power consumed by a data center and the power actually delivered to its IT equipment.

2.     Service proximity, because of which information travels shorter distances and reduction in energy consumption of the networking equipment that carries traffic.

3.     Self-scalability, because of the inherent nature of the network.

4.     Increased energy efficiency since No baseline power is used. That is, if we use gateways only when they are active, power consumption is proportional to the load leading to more efficiency than centralized servers.

5.     Residential GW PUE is 1.07 when compared to data center PUE of 1.2. Energy savings as high as 58%.

6.     Localized and personalized services can be provided to the end users.

Three key components used in VoD & simulation.

·       Gateways: provide storage, bandwidth resources.

·       The tracker: coordinates all VoD activities in NaDa.

·       Content servers: provide content to gateways and clients (if needed)

Content Placement Strategy

1.      Split the content into smaller chunks.

2.     Replicate the content across random gateways.

3.     Number of replicas determined by solving optimization problem based on the constraints on available upload and storage, number of clients, request rates etc.

4.     Popularity aware placement based hot/warm/cold strategies.

Hot: replicate on all gateways.

Warm: replication is done minimally

Cold: No proactive placement (Stays on servers)

Strengths

1.      The paper presents detailed analysis on the Nano data center philosophy. The experimental results tendered shows significant improvement in the energy savings which is the primary motivation of the paper.

2.     NaDa uses existing infrastructure which can significantly reduce load on conventional servers.

3.     Simulations done are using real time scenarios. Simulations demonstrated energy savings ranging from 20% to 60% versus data centers.

Weakness

1.      Uplink bandwidth is often limited. The paper does not provide any solution to this.

2.     Real time deployment- Since there are millions of gateways to manage using P2P architecture.

3.     Data privacy- Since centralized data centers are more secure physically and have advanced security measures implemented, how do we manage privacy of data at the gateways.

4.     Price of the gateway - The paper makes major assumption that the cost of replacing new gateways is less the cost(power cost) incurred in running the data center.

5.     Although the idea was very well received by some companies and academia, the project seems to have no success stories on the market yet.

Discussion points

1.      Privacy is major concern. How do we improve security and privacy at the edge/home gateways?

2.     Potential QoS issues moving control from content providers (YouTube) to ISPs. How do we resolve this?

3.     How do we manage the effects of consumer line overprovisioning ?

4.     How can we encourage users to agree on the NaDa philosophy ?