• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.192-194
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• 2013

가상화 기술의 발달은 클라우드 데이터센터(cloud datacenter)에서의 서버 통합(server consolidation)을 지원하며 이를 통하여 물리적 머신(physical machine, PM) 관리 비용을 감소시킬 수 있다. 그러나 서버가 통합됨에 따라 가상 머신(virtual machine, VM) 간섭이 생길 수 있고 이는 성능 감소의 원인이 된다. 따라서 VM 간섭과 PM 관리 비용을 감소시키는 것은 트레이드오프(trade-off)를 이루며 본 논문에서는 이를 해결하기 위하여 VM 간섭 계측(quantizing)을 위한 기법과 비용 효율적 VM 배치(placement)를 위한 휴리스틱(heuristics)을 제안한다.

• Journal of IKEEE
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• v.21 no.4
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• pp.353-357
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• 2017

In order to maintain numerous server systems used in enterprise and data center environments, the most important thing is to prevent the occurrence of UE (Uncorrectable Error) of each server system. With the recent development of cloud services, more memory modules are being used than ever before, while the operating frequency of server systems has increased and the process of developing memory has continued to shrink, making it more likely to fail. In these environments, there is a way to repair memory defects directly in the server system, but there is no currently available guideline to use it effectively. In this paper, we propose a method to effectively prevent memory failure in a server system based on the observation and analysis of memory failure phenomenon in existing system.

• KIISE Transactions on Computing Practices
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• v.22 no.2
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• pp.95-100
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• 2016

In the current era of big data and cloud computing, the amount of data utilized is increasing, and various systems to process this big data rapidly are being developed. A distributed file system is often used to store the data, and glusterFS is one of popular distributed file systems. As computer technology has advanced, NAND flash SSDs (Solid State Drives), which are high performance storage devices, have become cheaper. For this reason, datacenter operators attempt to use SSDs in their systems. They also try to install glusterFS on SSDs. However, since the glusterFS is designed to use HDDs (Hard Disk Drives), when SSDs are used instead of HDDs, the performance is degraded due to structural problems. The problems include the use of I/O-cache, Read-ahead, and Write-behind Translators. By removing these features that do not fit SSDs which are advantageous for random I/O, we have achieved performance improvements, by up to 255% in the case of 4KB random reads, and by up to 50% in the case of 64KB random reads.