DHTCache

DHTCache 1

A Distributed Cache Service Carlos E. Gómez carloseg@uniquindio.edu.co University of Quindio – Colombia

María del Pilar Villamil mavillam@uniandes.edu.co University of Los Andes - Colombia

Harold E. Castro hcastro@uniandes.edu.co University of Los Andes – Colombia

Laurent d’Orazio laurent.dorazio@isima.fr University Blaise Pascal – France

Content 2

DHT P2P systems and performance Related work The DHTCache Evaluation Conclusions and future work

Content 3

DHT P2P systems and performance Related work The DHTCache Evaluation Conclusions and future work

DHT P2P systems and performance 4

DHT systems

New generation of P2P systems.

Based on Distributed Hash Tables.

Object storage and location with scalability and efficiency.

Nodes form a overlay network.

DHT applications

Highly sophisticated.

More semantics on objects that handle.

High volume of data.

Highly distributed.

Need good performance

DHT Systems - Functional layers 5

DHT Systems - Functional layers 6

DHT Systems - Functional layers 7

DHT Systems - Functional layers 8

DHT Systems - Functional layers 9

Cache 10

Enhancing the performance.

Shorter path for retrieval a object.

If the system is layered, the cache is present across all layers.

Different information can be cached depending on the layer.

Emerges the idea of cooperative cache vertical and horizontal.

Motivation and objective 11

It is very difficult to configure a cache since there are

many parameters:

Size.

Replacement Policy.

Topology of the distributed cache.

Resolution protocol.

Is very complex to fine tune, specially when it is dynamic

and distributed.

Content 12

DHT P2P systems and performance

Related work The DHTCache Evaluation Conclusions and future work

Related work 13

Diverse proposals about

distributed caches:

Cache in P2P systems

DHTSystems used as caches of other P2P systems P2P systems that they are implemented inside a cache

Benefits

Adaptable cache services

Reduce the network use Improve the response time Ameliorate popular queries Reduce processing cost

But

Cache configuration?

How to provide cooperation between heterogeneous caches?

This information in not clear and it is difficult to reuse these solutions

Content 14

DHT P2P systems and performance Related work

The DHTCache Evaluation Conclusions and future work

The DHTCache (1) 15

Is a distributed cache service placed on top of DHT Systems.

It has different types of caches according to the layers of

DHTSystems.

It takes into account advanced caching techniques, particularly

cooperative caching.

It allows to experiment cache configurations in order to tune

caches according to a specific context.

The DHTCache (2) 16

It supports make decisions about of cache suitable for

developing in a particular DHTApplication.

It is transparent for the DHTApplications.

It intercepts get and put messages.

When a cache miss occurs, it forwards the get message.

Operation of DHTCache 17

Typical Node 18

Functions of the DHTCache 19

Internal functions

Internal functions

The put operation

Record the events

The get operation

Analyzer component

The put operation 20

The put operation 21

The put operation 22

The put operation 23

The get Operation 24

The get Operation 25

The get Operation 26

The get Operation 27

The get Operation 28

The get Operation 29

The get Operation 30

The get Operation 31

Content 32

DHT P2P systems and performance Related work The DHTCache

Evaluation Conclusions and future work

Evaluation 33

Evaluation of the DHTCache is a twofold issue: Non-functional features: Flexibility (plain files).

Usage is the same that FreePastry.

Portability and scalability.

Capability of a developer to make decisions based on the information provided.

Scenario of the Evaluation 34

A third-party DHTApplication was used Several experiments were performed with different

number of nodes and different cache configurations.

Nodes: 400, 600 and 800.

Objects: 1000.

Cache size: 200, 400 and 600 objects.

Replacement Policy: FIFO and LRU. Cache size was a fixed fraction of the objects within the system.

Results obtained in terms of hit rate.

Results 35

DHTSystem of 600 nodes

DHTSystem of 600 nodes

It is important to note: Developers are responsible for analyzing metrics The results are highly dependent of the DHTApplication

Content 36

DHT P2P systems and performance Related work The DHTCache Evaluation

Conclusions and future work

Conclusions 37

DHTCache is a making decisions tool.

DHTCache provides metrics to the developer to facilitate the

identification of one appropriate cache configuration.

DHTCache takes into account techniques as cooperative caching.

A first prototype of the DHTCache is functional and allows

validating the ideas of this proposal.

A first performance evaluation using several cache parameters and

different number of nodes.

Future work 38

The development of cache within the DLS layer and its

interaction with caching within the DSS layer.

One easier way to specify the distributed cache topology.

One mechanism for automatically defining new metrics

and gathering the log files.

New scenarios with more peers and more nodes to probe

the scalability of DHTCache.

DHTCache

Thank you very much!

Questions!

Carlos E. G贸mez carloseg@uniquindio.edu.co