This thesis studies the area of virtualization. The focus is on the sub-area live migration, a technique that allows a seamless migration of a virtual machine from one physical machine to another physical machine. Virtualization is an attractive technique, utilized in large computer systems, for example data centers. By using live migration, data center administrators can migrate virtual machines, seamlessly, without the users of the virtual machines taking notice about the migrations. Manually initiated migrations can become cumbersome, with an ever-increasing number of physical machines. The number of physical and virtual machines is not the only problem, deciding when to migrate and where to migrate are other problems that needs to be solved. Manually initiated migrations can also be inaccurate and untimely. Two different strategies for automated live migration have been developed in this thesis. The Push and the Pull strategies. The Push strategy tries to get rid of virtual machines and the Pull strategy tries to steal virtual machines. Both of these strategies, their design and implementation, are presented in the thesis. The strategies utilizes Shannon's Information Entropy to measure the balance in the system. The strategies further utilizes a cost model to predict the time a migration would require. This is used together with the Information Entropy to decide which virtual machine to migrate if and when a hotspot occurs. The implementation was done with the help of OMNeT++, an open-source simulation tool. The strategies are evaluated with the help of a set of simulations. These simulations include a variety of scenarios with different workloads. Our results shows that the developed strategies can re-balance a system of computers, after a large amount of virtual machines has been added or removed, in only 4-5 minutes. The results further shows that our strategies are able to keep the system balanced when the system load is at medium. This while virtual machines are continuously added or removed from the system. The contribution this thesis brings to the field is a model for how automated live migration of virtual machines can be done to improve the performance of a computer system, for example a data center.

Submitted by Fabiane Tessari Lima da Silva (tfabit@hotmail.com) on 2016-10-12T21:12:43Z No. of bitstreams: 1 Dissertação FTLS.pdf: 3016620 bytes, checksum: f0a286bd1e78858fbbc5446deafe0795 (MD5) / Rejected by Renata de Souza Nascimento (renata.souza@fgv.br), reason: Fabiane, boa tarde Conforme contato telefônico, será necessário alguns ajustes para que possamos aprovar seu trabalho. Antes de tudo, o trabalho precisa estar com a ficha catalográfica, após a contracapa. Essa ficha se refere ao passo 1 do e-mail, que é encaminhada pela biblioteca. Referente à Introdução, encaminharei em seu e-mail um modelo de como a capa e folha de assinaturas devem estar. Referente à numeração, está correta aparecer somente na Introdução. Mas por exemplo, se a Introdução for a página 8, deverá incluir o numero 8 e seguir. Após alterações, realizar nova submissão. Att on 2016-10-13T16:34:56Z (GMT) / Submitted by Fabiane Tessari Lima da Silva (tfabit@hotmail.com) on 2016-10-13T18:09:52Z No. of bitstreams: 1 Dissertação FTLS(final).pdf: 3359595 bytes, checksum: a8dbe502981c51415d27a87ead6eac44 (MD5) / Rejected by Renata de Souza Nascimento (renata.souza@fgv.br), reason: Fabiane, Na capa, anterior ao seu nome falta incluir o nome da Fundação e da Escola. Att on 2016-10-13T23:25:00Z (GMT) / Submitted by Fabiane Tessari Lima da Silva (tfabit@hotmail.com) on 2016-10-13T23:56:58Z No. of bitstreams: 1 DISSERTAÇÃO.pdf: 3141661 bytes, checksum: 8ce76beb2a4c0ae2c45ab02b7bf84d36 (MD5) / Approved for entry into archive by Renata de Souza Nascimento (renata.souza@fgv.br) on 2016-10-14T00:02:10Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO.pdf: 3141661 bytes, checksum: 8ce76beb2a4c0ae2c45ab02b7bf84d36 (MD5) / Made available in DSpace on 2016-10-14T12:46:59Z (GMT). No. of bitstreams: 1 DISSERTAÇÃO.pdf: 3141661 bytes, checksum: 8ce76beb2a4c0ae2c45ab02b7bf84d36 (MD5) Previous issue date: 2016-09-09 / Law number 12.815/2013, current legal guide of the port sector in Brazil, had as its most important innovation, the opening of competition to the port different terminals, exposed to numerous political regimes: private and public law. Furthermore, the sector of ports innovated by establishing that the element of delimitation of another regime is the polygonal design of the organized ports - task assigned to the Public Administration. As a result, terminals exposed to public law (operated by lessees) are now subjected to competition not originally advised and under uneven conditions, running the risk of having contractual divergences – as seen in some actual cases. Analyzing the parameters that advises the Administrators in the task of re-defying these polygonal – which determines the competitive environment –, we can come to the conclusion that the Organized Port of Paranagua' s lessees injured have assured the right to the immediate contractual re-balance. / A Lei nº 12.815/2013, atual marco legal do setor portuário no Brasil, teve como principal inovação a abertura da concorrência a operadores submetidos a regimes jurídicos diversos: autorizatários (direito privado) e arrendatários/concessionários (direito público). Em segundo lugar, inovou estabelecendo que o elemento delimitador da incidência de um ou outro regime jurídico é o desenho das poligonais dos portos organizados, tarefa esta atribuída à Administração Pública. Como consequência, este diploma legal gerou (ou tem potencial de gerar) significativos impactos operacionais sobre os arrendatários do setor, que passaram a ser submetidos à concorrência inicialmente não prevista sob condições desiguais, havendo o risco de desequilíbrio contratual – como ilustram alguns casos concretos. Analisando os parâmetros que orientam o Administrador na tarefa de redefinição das poligonais – que, por sua vez, determina o ambiente concorrencial –, conclui-se pela possibilidade de os arrendatários do Porto Organizado de Paranaguá porventura prejudicados pleitearem o imediato reequilíbrio contratual.

In this thesis we investigate the problem of portfolio re-balancing for fixed periods using a cost/risk adaptation model and stochastic optimization. The cost/risk adaptation model takes theory of optimal liquidity costs and risk preference to build a universe in which we try to find better strategies than conventional ones. The results are focused on the comparison between the conventional execution strategies versus our developed model. We have found that our model outperforms the conventional methods for all assets that has been evaluated, and especially for investors whom value exposure to the markets higher.