• Ei tuloksia

This section presents some suggestions for the future development of CloudSimDisk.

At rst, real case scenarios should be performed using benchmarking tool to mea-sure the energy consumption of a specic HDD under dierent workload. Similar scenarios should be run using CloudSimDisk module and results should be compared with real world measures.

Then, models should be expanded to improve modeling of modern HDDs, including read/write dierentiation, internal buer and spin-down capability. Also, while the seek time is one of the most important performance specication, it is a challenging task to model it accurately. In fact, this time is not linear and, for each operation, it is aected by a multitude of factors, including the size of the le to process, the disk fragmentation, the le system type or even performed operation (read or write).

Thus, new parameters should be implemented in CloudSimDisk.

Furthermore, the network package in CloudSim could be linked with CloudSimDisk to model the network latency between servers and the persistent storage, and its related energy consumption. However, this amount of energy consumed should not be merged with the current persistent storage energy consumption. The modularity of the implementation should be preserved; the network is an independent part of the data center architecture.

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CloudSimDisk has been developed on Eclipse Luna SR2 (4.4.2), Windows 64 Bit.

The entire source code is available on GitHub at https://github.com/Udacity2048/

CloudSimDisk (see Figure A1.1).

Figure A1.1. CloudSimDisk home page on GitHub.

CloudSimDisk JavaDoc is provided in the docs folder. The required jar les are gath-ered in the jars folder. The files folder contains necessary les for CloudSimDisk simulation examples (request arrival times, data le names and sizes, Wikipedia trace, etc).

Future improvements of CloudSimDisk will be uploaded on this repository. Also, this github will contain discussion threads about potential issues, general questions and new ideas, and a wiki page providing detail information on the most raised questions.

(continues)

The CloudSim core simulation engine is provided with CloudSimDisk (see Figure A1.2) because several Java Access Modiers had to be changed from "Private" to

"Protected" in order to allow class extensions for CloudSimDisk.

Figure A1.2. CloudSim core simulation engine on CloudSimDisk GitHub repository.

As a start, a new user should run MyExample0. This example aims to understand the basic execution of CloudSimDisk simulations. The scenario consists of 1 request, sent to the data center at 0.5 second. The request contains 1 FileA of 1 MB that need to be stored. The persistent storage is composed of 1 HDD (Seagate Enterprise 6TB Ref:ST6000VN0001). No les are retrieved. No le needed in the storage system before the simulation start.

The example can be nd in cloudsimdisk.examples package. The expected output of the simulation is depicted in Figure A2.1. Note that the time at which the le is added (0.527915 second) can be dierent for the reason that the transaction time (0.027915 second) depends on the randomness of the seek time and the rotation latency. Hence, the energy consumed (0.315 Joule) can vary too.

Figure A2.1. CloudSimDisk console output for "MyExample0".

This appendix section presents the source code of an HDD model implemented in CloudSimDisk (see Figure A3.1). Each HDD model is following the same pattern.

The brand and the reference of the modeled disk are included in the name of the class. Thus, the user knows which disk is modeled by this class.

The core of the class is formed by a "switch-case" statement where each case cor-responds to one disk characteristic. Later, the user can add new characteristics by adding new cases.

Figure A3.1. CloudSimDisk HDD model of the Seagate Enterprise NAS 6TB (Ref:

ST6000VN0001).

Then, the abstract class StorageModelHdd implements one method for each HDD characteristic (see Figure A3.2). The name of these methods are semantically un-derstandable for the end user.

(continues)

Figure A3.2. The abstract class extended by all Hard Disk Drive models.

This appendix section presents the source code of an HDD power model implemented in CloudSimDisk (see Figure A4.1). Each HDD power model is following the same pattern. The brand and the reference of the modeled disk are included in the name of the class. Thus, the user knows which disk is modeled by this class.

The core of the class is formed by a "switch-case" statement where each case cor-responds to the power consumption in one specic operating mode. Later, the user can add new power data by adding new cases.

Figure A4.1. CloudSimDisk HDD power model of the HGST Ultrastar 900GB (Ref:

HUC109090CSS600).

Then, the abstract class PowerModelHdd implements one method for each power mode (see Figure A4.2). The name of these methods are semantically understand-able for the end user.

(continues)

Figure A4.2. The abstract class extended by all Hard Disk Drive power models.