A fast and slippery slope for file systems

There is a vast number and variety of file systems cur-rently available, each optimizing for an ever growing number of storage devices and workloads. Users have an unprece-dented, and somewhat overwhelming, number of data man-agement options. At the same time, the fastest storage de-vices are only getting faster, and it is unclear on how well the existing file systems will adapt. Using emulation tech-niques, we evaluate five popular Linux file systems across a range of storage device latencies typical to low-end hard drives, latest high-performance persistent memory block de-vices, and in between. Our findings are often surprising. De-pending on the workload, we find that some file systems can clearly scale with faster storage devices much better than others. Further, as storage device latency decreases, we find unexpected performance inversions across file systems. Finally, file system scalability in the higher device latency range is not representative of scalability in the lower, sub-millisecond, latency range. We then focus on Nilfs2 as an especially alarming example of an unexpectedly poor scala-bility and present detailed instructions for identifying bottle-necks in the I/O stack

Revenue Driven Resource Allocation for Virtualized Data Centers

Abstract—The increasing VM density in cloud hosting services makes careful management of physical resources such as CPU, memory, and I/O bandwidth within individual virtualized servers a priority. To maximize cost-efficiency, resource management needs to be coupled with the revenue generating mechanisms of cloud hosting: the service level agreements (SLAs) of hosted client applications. In this paper, we develop a server resource man-agement framework that reduces data center resource manage-ment complexity substantially. Our solution implements revenue-driven dynamic resource allocation which continuously steers the resource distribution across hosted VMs within a server such as to maximize the SLA-generated revenue from the server. Our experimental evaluation for a VMware ESX hypervisor highlights the importance of both resource isolation and resource sharing across VMs. The empirical data shows a 7%-54 % increase in total revenue generated for a mix of 10-25 VMs hosting either similar or diverse workloads when compared to using the currently available resource distribution mechanisms in ESX. I

BORG: Block-reORGanization and Self-optimization in Storage Systems

This paper presents the design, implementation, and evaluation of BORG, a self-optimizing storage system that performs automatic block reorganization based on the observed I/O workload. BORG is motivated by three characteristics of I/O workloads: non-uniform access frequency distribution, temporal locality, and partial determinism in non-sequential accesses. To achieve its objective, BORG manages a small, dedicated partition on the disk drive, with the goal of servicing a majority of the I/O requests from within this partition with significantly reduced seek and rotational delays. BORG is transparent to the rest of the storage stack, including applications, file system(s), and I/O schedulers, thereby requiring no or minimal modification to storage stack implementations. We evaluated a Linux implementation of BORG using several real-world workloads, including individual user desktop environments, a web-server, a virtual machine monitor, and an SVN server. These experiments comprehensively demonstrate BORG’s effectiveness in improving I/O performance and its incurred resource overhead

Diosgenin, a Steroidal Saponin, Inhibits Migration and Invasion of Human Prostate Cancer PC-3 Cells by Reducing Matrix Metalloproteinases Expression

BACKGROUND: Diosgenin, a steroidal saponin obtained from fenugreek (Trigonella foenum graecum), was found to exert anti-carcinogenic properties, such as inhibiting proliferation and inducing apoptosis in a variety of tumor cells. However, the effect of diosgenin on cancer metastasis remains unclear. The aim of the study is to examine the effect of diosgenin on migration and invasion in human prostate cancer PC-3 cells. METHODS AND PRINCIPAL FINDINGS: Diosgenin inhibited proliferation of PC-3 cells in a dose-dependent manner. When treated with non-toxic doses of diosgenin, cell migration and invasion were markedly suppressed by in vitro wound healing assay and Boyden chamber invasion assay, respectively. Furthermore, diosgenin reduced the activities of matrix metalloproteinase-2 (MMP-2) and MMP-9 by gelatin zymography assay. The mRNA level of MMP-2, -9, -7 and extracellular inducer of matrix metalloproteinase (EMMPRIN) were also suppressed while tissue inhibitor of metalloproteinase-2 (TIMP-2) was increased by diosgenin. In addition, diosgenin abolished the expression of vascular endothelial growth factor (VEGF) in PC-3 cells and tube formation of endothelial cells. Our immunoblotting assays indicated that diosgenin potently suppressed the phosphorylation of phosphatidylinositide-3 kinase (PI3K), Akt, extracellular signal regulating kinase (ERK) and c-Jun N-terminal kinase (JNK). In addition, diosgenin significantly decreased the nuclear level of nuclear factor kappa B (NF-κB), suggesting that diosgenin inhibited NF-κB activity. CONCLUSION/SIGNIFICANCE: The results suggested that diosgenin inhibited migration and invasion of PC-3 cells by reducing MMPs expression. It also inhibited ERK, JNK and PI3K/Akt signaling pathways as well as NF-κB activity. These findings reveal new therapeutic potential for diosgenin in anti-metastatic therapy

Department of Energy Project ER25739 Final Report QoS-Enabled, High-performance Storage Systems for Data-Intensive Scientific Computing

This project's work resulted in the following research projects: (1) BORG - Block-reORGanization for Self-optimizing Storage Systems; (2) ABLE - Active Block Layer Extensions; (3) EXCES - EXternal Caching in Energy-Saving Storage Systems; (4) GRIO - Guaranteed-Rate I/O Scheduler. These projects together help in substantially advancing the over-arching project goal of developing 'QoS-Enabled, High-Performance Storage Systems'

Department of Energy Project ER25739 Final Report

This project's work resulted in the following research projects: (1) BORG - Block-reORGanization for Self-optimizing Storage Systems; (2) ABLE - Active Block Layer Extensions; (3) EXCES - EXternal Caching in Energy-Saving Storage Systems; (4) GRIO - Guaranteed-Rate I/O Scheduler. These projects together help in substantially advancing the over-arching project goal of developing 'QoS-Enabled, High-Performance Storage Systems'