http://smartech.gatech.edu/handle/1853/79 Reports published by researchers associated with the Center Search the Channel search http://smartech.gatech.edu/simple-search http://smartech.gatech.edu/handle/1853/20116 Title: A Recovery Conscious Framework for Fault Resilient Storage Systems <br/> <br/>Authors: Seshadri, Sangeetha; Liu, Ling; Chiu, Lawrence; Constantinescu, Cornel; Balachandran, Subashini <br/> <br/>Abstract: In this paper we present a recovery-conscious framework for improving the fault resiliency and recovery efficiency of highly concurrent embedded storage software systems. Our framework consists of a three-tier architecture and a suite of recovery conscious techniques. In the top tier, we promote fine-grained recovery at the task level by introducing recovery groups to model recovery dependencies between tasks. At the middle tier we develop highly effective mappings of dependent tasks to processor resources through careful tuning of recovery efficiency sensitive parameters. At the bottom tier, we advocate the use of recovery-conscious scheduling by careful serialization of dependent tasks, which provides high recovery efficiency without sacrificing system performance. We develop a formal model to guide the understanding and the development of techniques for effectively mapping fine-grained tasks to system resources, aiming at reducing the ripple effect of software failures while sustaining high performance even during system recovery. Our techniques have been implemented on a real industry-standard storage system. Experimental results show that our techniques are effective, non-intrusive and can significantly boost system resilience while delivering high performance. Sun, 29 Oct 2006 22:58:59 GMT http://smartech.gatech.edu/handle/1853/20115 Title: O2S2: Enhanced Object-based Virtualized Storage <br/> <br/>Authors: Raj, Himanshu; Schwan, Karsten <br/> <br/>Abstract: Object based storage devices (OSDs) elevate the level of abstraction presented to clients, thereby permitting them to offer methods for managing, sharing, and securing information that go beyond those offered by block-based stores. The Object-Oriented Storage System (O2S2) architecture presented and evaluated in this paper implements a virtualization service to provide object-based storage in a virtualized environment. This service provides a virtual object-based storage device (vOSD) to virtual machines. The use of vOSDs permits the service provider, i.e., the vOSD storage domain, to offer to guest virtual machines new methods for resource management and consolidation, without requiring the purchase of physical storage devices that faithfully implement OSD functionality. Methods demonstrated in this paper include improved support for access control and for heterogeneity of storage devices. Advantages derived from such methods also include reduced complexity for end clients, i.e., guest VMs. A prototype PVFS-based O2S2 implementation demonstrates that its enhanced services can be provided at low cost, enabled in part by the effcient utilization of otherwise idle domain resources. Sun, 29 Oct 2006 22:58:59 GMT http://smartech.gatech.edu/handle/1853/20114 Title: M-Channels and M-Brokers: New Abstractions for Co-ordinated Management in Virtualized Systems <br/> <br/>Authors: Kumar, Sanjay; Nathuji, Ripal; Schwan, Karsten; Talwar, Vanish; Ranganathan, Partha <br/> <br/>Abstract: Management and automation are important issues in enterprise environments, often consuming the largest fraction of the overall IT budget. A key challenge here is co-ordination across multiple management solutions deployed in different management domains, including across hardware and software, across different levels of abstraction, and across different hosts. This paper makes three contributions to addressing this problem. First, we propose a novel management co-ordination architecture for virtualized environments. Our architecture includes two powerful abstractions – m-channels, which provide mechanisms for communication between the hardware, virtual machines, and applications and m-brokers, which allow high-level policy co-ordination across different management agents. Second, we discuss Dom-M, an instantiation of our architecture in the context of the Xen hypervisor, and identify tradeoffs between different implementations of such management domains. Finally, to demonstrate the effectiveness of our approach, we implement and evaluate different cross-level solutions for power management using our abstractions, and also discuss qualitatively other applications including storage backup, inventory management, and trust management. Sun, 29 Oct 2006 22:58:59 GMT http://smartech.gatech.edu/handle/1853/20113 Title: VMedia: Enhanced Multimedia Services in Virtualized Systems <br/> <br/>Authors: Raj, Himanshu; Seshasayee, Balasubramanian; Schwan, Karsten <br/> <br/>Abstract: This paper presents the VMedia multimedia virtualization framework, for sharing media devices among multiple virtual machines (VMs). The framework provides logical media devices to virtual machines. These devices are exported via a well defined, higher level, multimedia access interface to the applications and operating system running in a virtual machine. By using semantically meaningful information, rather than low-level raw data, within the VMedia framework, efficient virtualization solutions can be created for physical devices shared by multiple virtual machines. Experimental results demonstrate that the base cost of virtual device access via VMedia is small compared to native physical device access, and in addition, that these costs scale well with an increasing number of guest VMs. Here, VMedia’s MediaGraph abstraction is a key contributor, since it also allows the framework to support dynamic restructuring, in order to adapt device accesses to changing requirements. Finally, VMedia permits platforms to offer new and enhanced logical device functionality at lower costs than those achievable with alternative solutions. Sun, 29 Oct 2006 22:58:59 GMT