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<p>Nuvarande implementationer av distribuerade hashtabeller (DHT) har en begränsad storlek för data som kan lagras, som t.ex. OpenDHTs datastorleks gräns på 1kByte. Är det möjligt att lagra filer större än 1kByte med DHT-tekniken? Finns det någon lösning för att skydda de data som lagrats utan att försämra prestandan? Vår lösning var att utveckla en klient- och servermjukvara. Mjukvaran använder sig av DHT tekniken för att dela upp filer och distribuera delarna över ett serverkluster. För att se om mjukvaran fungerade som tänkt, gjorde vi ett test utifrån de inledande frågorna. Testet visade att det är möjligt att lagra filer större än 1kByte, säkert med DHT tekniken utan att förlora för mycket prestanda.</p> / <p>Currently existing distributed hash table (DHT) implementations use a small storage size for data, such as OpenDHT’s storage size limitation of 1kByte. Is it possible to store larger files than 1kByte using the DHT technique? Is there a way to protect the data without losing to much performance? Our solution was to develop a client and server software. This software uses the DHT technique to split files and distribute their parts across a cluster of servers. To see if the software worked as intended we created a test based on our opening questions. This test shows that it indeed is possible to store large files securely using the DHT technique without losing any significant performance.</p>

Historically, cryptographic file systems have been several times slower than non-cryptographic file systems. This paper describes the design and implementation of a fast Cryptographic Log-structured File System on OpenBSD. We experimentally demonstrate that our pro-totype file system performs close to the Fast File System (FFS) and the Log-structured File System (LFS). To increase performance, our file system performs most encryption and decryption work during disk read and write operations. This is possible thanks to the SEAL encryption algorithm, a software optimized stream cipher that allows the en-cryption work to be performed prior to the actual data is available. We believe that our cryptographic file system design is ideal for optimal read and write performance on locally stored confidential data. / Denna uppsats beskriver utvecklingen av ett kryptografiskt log-strukturerat filsystem och vi visar genom experiment att dess prestanda är jämförbar med lokala filsystem. / Karl Knutsson Skiftesgatan 40 332 35 Gislaved Sweden

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I det här arbetet har författarna valt att fokusera på lagringssäkerhet ur synvinkelnhemmiljö. För att kunna ge målgruppen någon form av riktlinje definieras olika kravpå säkerhet och lagring från författarnas sida att utgå från vid diskussion och arbetetsupplägg. Arbetet inriktar sig på vad det finns för möjligheter för att kunna säkra uppde olika formerna av lagringsmöjligheter. Är det möjligt att göra? Vilka källor kanman förvänta sig att målgruppen använder för att lösa de här problemen? Genom attstudera tidigare forskning och göra omfattande dokumentstudier kommer författarnafram till vad som kan vara lämpligt att använda i en hemmiljö för säker fillagring.Arbetet mynnar ut i ett resultat med vad de olika lagringslösningarna och lagringstjänsternaklarar av för krav samt vad de klarar av för olika funktioner. Det finns ävenen form av rekommendation för användaren vad som kan vara en lämplig väg att gå,dock inte ett direkt svar på hur denna skall se ut. / The authors of this essay have chosen to focus on secure data storage from a homeenvironment standpoint. In order to give this target group something that resembles aguideline, several demands regarding security and storage will be defined. This willalso be used as a basis both for how the essay is approached and the discussion of it.The essay focuses on the possibilities when it comes to securing the varyingforms of storage solutions. Can it be done securely? In order to solve these problems,what sources are the target group most likely to use?Through study of earlier research, and extensive document studies, the authorsfind solutions regarding secure data storage that are feasible to use in a home environment.In the end, the essay will point out which of the defined demands thevarious storage solutions and services can handle, and which functions they can handle.There is also a recommendation for the reader regarding what is feasible andsuitable for use, though not a clear-cut answer saying which solution is the better;that’s still up to the reader herself to determine.

O armazenamento de arquivos e dados está seguindo um paradigma de mudança para a Internet utilizando a nuvem. Porém, este processo ainda gera algumas dúvidas em relação à segurança e a disponibilidade dos arquivos. Este projeto de mestrado propõe criar uma camada de abstração entre diversos servidores de armazenamento público, sem infraestrutura adicional, e possibilitar ao usuário comum um método de armazenamento distribuído, com maior redundância e segurança se comparada às abordagens atuais de armazenamento. Outro aspecto importante deste projeto foi criar uma ferramenta que seja flexível o suficiente para ser fácil de ser utilizada por outros pesquisadores para avaliar novas técnicas de armazenamento e seleção automática de estratégias de dispersão. Este projeto foi feito utilizando conceitos de dispersão de arquivos e de mecanismos de seleção automática utilizando atributos de QoS. A primeira contribuição foi um protótipo denominado FlexSky que implementa os mecanismos de dispersão utilizados. Devido a quantidade grande de parâmetros para se escolher no processo de dispersão, foi necessário desenvolver um mecanismo que reduzisse a quantidade de parâmetros para que um usuário comum consiga utilizar a ferramenta. Este mecanismo foi a segunda contribuição (MSSF), no qual foi criado um modelo baseado em otimização linear inteira para realizar a seleção automática de estratégias de armazenamento multinuvem. Para se avaliar as contribuições foram propostos testes qualitativos de usabilidade da ferramenta e teste quantitativos de desempenho dos processos da ferramenta. Os resultados sugerem que a ferramenta FlexSky facilitou o estudo destes mecanismos de dispersão e possibilita uma avaliação de desempenho deles. Jà o MSSF consegue a partir de atributos de QoS escolher uma estratégia ótima que maximize os parâmetros desejados do processo de dispersão para diversos casos considerando diferentes quantidades de módulos e de provedores. / Data and file storage is moving to the Internet using the cloud approach. However, this process still creates issues related to security and availability. This project creates an abstraction layer among several public storage servers, without the need for additional infrastructure, enabling regular users to use a distributed storage method with increased redundancy and security comparing to current techniques. Another important aspect of this project was to create a tool flexible enough to be easy for other researchers to evaluate new dispersal techniques. The first contribution was a prototype named FlexSky, which implements the studied dispersal mechanisms. Due to the big amount of parameters to choose from during the dispersal process, it was needed to develop a mechanism to reduce the amount of user input parameters so a regular user can use the tool. This mechanism was the second contribution (MSSF) and it is composed of a model based on integer linear optimization that automatically selects multicloud dispersal strategies. The evaluation phase was composed of qualitative usability tests and quantitative performance tests. The results suggests that the FlexSky tool made the study of dispersal mechanisms easier and enables to evaluate their performance. MSSF results shown that using QoS attributes, MSSF can choose an optimal dispersal strategy which maximizes and minimizes the required QoS attributes considering several modules and providers.

O armazenamento de arquivos e dados está seguindo um paradigma de mudança para a Internet utilizando a nuvem. Porém, este processo ainda gera algumas dúvidas em relação à segurança e a disponibilidade dos arquivos. Este projeto de mestrado propõe criar uma camada de abstração entre diversos servidores de armazenamento público, sem infraestrutura adicional, e possibilitar ao usuário comum um método de armazenamento distribuído, com maior redundância e segurança se comparada às abordagens atuais de armazenamento. Outro aspecto importante deste projeto foi criar uma ferramenta que seja flexível o suficiente para ser fácil de ser utilizada por outros pesquisadores para avaliar novas técnicas de armazenamento e seleção automática de estratégias de dispersão. Este projeto foi feito utilizando conceitos de dispersão de arquivos e de mecanismos de seleção automática utilizando atributos de QoS. A primeira contribuição foi um protótipo denominado FlexSky que implementa os mecanismos de dispersão utilizados. Devido a quantidade grande de parâmetros para se escolher no processo de dispersão, foi necessário desenvolver um mecanismo que reduzisse a quantidade de parâmetros para que um usuário comum consiga utilizar a ferramenta. Este mecanismo foi a segunda contribuição (MSSF), no qual foi criado um modelo baseado em otimização linear inteira para realizar a seleção automática de estratégias de armazenamento multinuvem. Para se avaliar as contribuições foram propostos testes qualitativos de usabilidade da ferramenta e teste quantitativos de desempenho dos processos da ferramenta. Os resultados sugerem que a ferramenta FlexSky facilitou o estudo destes mecanismos de dispersão e possibilita uma avaliação de desempenho deles. Jà o MSSF consegue a partir de atributos de QoS escolher uma estratégia ótima que maximize os parâmetros desejados do processo de dispersão para diversos casos considerando diferentes quantidades de módulos e de provedores. / Data and file storage is moving to the Internet using the cloud approach. However, this process still creates issues related to security and availability. This project creates an abstraction layer among several public storage servers, without the need for additional infrastructure, enabling regular users to use a distributed storage method with increased redundancy and security comparing to current techniques. Another important aspect of this project was to create a tool flexible enough to be easy for other researchers to evaluate new dispersal techniques. The first contribution was a prototype named FlexSky, which implements the studied dispersal mechanisms. Due to the big amount of parameters to choose from during the dispersal process, it was needed to develop a mechanism to reduce the amount of user input parameters so a regular user can use the tool. This mechanism was the second contribution (MSSF) and it is composed of a model based on integer linear optimization that automatically selects multicloud dispersal strategies. The evaluation phase was composed of qualitative usability tests and quantitative performance tests. The results suggests that the FlexSky tool made the study of dispersal mechanisms easier and enables to evaluate their performance. MSSF results shown that using QoS attributes, MSSF can choose an optimal dispersal strategy which maximizes and minimizes the required QoS attributes considering several modules and providers.

Nuvarande implementationer av distribuerade hashtabeller (DHT) har en begränsad storlek för data som kan lagras, som t.ex. OpenDHTs datastorleks gräns på 1kByte. Är det möjligt att lagra filer större än 1kByte med DHT-tekniken? Finns det någon lösning för att skydda de data som lagrats utan att försämra prestandan? Vår lösning var att utveckla en klient- och servermjukvara. Mjukvaran använder sig av DHT tekniken för att dela upp filer och distribuera delarna över ett serverkluster. För att se om mjukvaran fungerade som tänkt, gjorde vi ett test utifrån de inledande frågorna. Testet visade att det är möjligt att lagra filer större än 1kByte, säkert med DHT tekniken utan att förlora för mycket prestanda. / Currently existing distributed hash table (DHT) implementations use a small storage size for data, such as OpenDHT’s storage size limitation of 1kByte. Is it possible to store larger files than 1kByte using the DHT technique? Is there a way to protect the data without losing to much performance? Our solution was to develop a client and server software. This software uses the DHT technique to split files and distribute their parts across a cluster of servers. To see if the software worked as intended we created a test based on our opening questions. This test shows that it indeed is possible to store large files securely using the DHT technique without losing any significant performance.

„Studentų darbų įkėlimo ir kaupimo sistema“ - tai sistema kuri palengvina darbą dėstytojams su studentų darbų įkėlimu ir jų kaupimu. Dėstytojai kuria modulius ir atsiskaitymus jiems. Moduliams gali priskirti studentus, arba suteikti galimybe patiems studentams prisiregistruoti prie modulio, žinant modulio raktą. Parsisiųsti ar ištrinti atsiskaitymų failus. Importuoti, eksportuoti vartotojus. Nustatyti kokio dydžio, tipo failus galima įkelti į sistemą. Studentai gali užsiregistruoti moduliui, jei žino modulio raktą. Peržiūrėti kokie moduliai priskirti, kokie atsiskaitymai jiems sukurti. Įkelti atsiskaitymams failus. Peržiūrėti įkeltų failų sąrašą. / “Students Works Loading and Storage System“ a system that facilitate the work of students and university professors with file uploads and their accumulation. Teachers can create modules, assignments. Enroll users to modules. Set upload time limit, visibility, max file size and file type to assignments. Delete or download uploaded files. Import, export or delete users. Students may register to module. In one place see all attached modules and assignments, upload files. See the list of uploaded files.

Virtualization is a technique that allows several virtual machines (VMs) to run on a single physical machine (PM) by adding a virtualization layer above the physical host&apos;s hardware. Many virtualization products allow a VM be migrated from one PM to other PM without interrupting the services running on the VM. This is called live migration and offers many potential advantages like server consolidation, reduced energy consumption, disaster recovery, reliability, and efficient workflows such as &quot;Follow-the-Sun&apos;&apos;. At present, the advantages of VM live migration are limited to Local Area Networks (LANs) as migrations over Wide Area Networks (WAN) offer lower performance due to IP address changes in the migrating VMs and also due to large network latency. For scenarios which require migrations, shared storage solutions like iSCSI (block storage) and NFS (file storage) are used to store the VM&apos;s disk to avoid the high latencies associated with disk state migration when private storage is used. When using iSCSI or NFS, all the disk I/O operations generated by the VM are encapsulated and carried to the shared storage over the IP network. The underlying latency in WAN will effect the performance of application requesting the disk I/O from the VM. In this thesis our objective was to determine the performance of shared and private storage when VMs are live migrated in networks with high latency, with WANs as the typical case. To achieve this objective, we used Iometer, a disk benchmarking tool, to investigate the I/O performance of iSCSI and NFS when used as shared storage for live migrating Xen VMs over emulated WANs. In addition, we have configured the Distributed Replicated Block Device (DRBD) system to provide private storage for our VMs through incremental disk replication. Then, we have studied the I/O performance of the private storage solution in the context of live disk migration and compared it to the performance of shared storage based on iSCSI and NFS. The results from our testbed indicate that the DRBD-based solution should be preferred over the considered shared storage solutions because DRBD consumed less network bandwidth and has a lower maximum I/O response time.