Leveraging redundant resources is a common means of addressing availability requirements, but it often implies redundant costs as well. At the same time, virtualization technologies are bursting into data centers with the promise of reducing costs through resource consolidation. Can virtualization and High Availability (HA) technologies be combined to optimize availability while mini...

Creating a cost-effective large-scale multi-tier Enterprise service requires judicious selection and configuration of infrastructure elements and mechanisms. The minimum cost solution that satisfies business requirements for service availability and performance should be identified. Emerging self-managed computing utility environments demand an automated solution to this problem. This solution ...

Pessimistic quorum-based data replication strategies generally strive for maximizing operation availabilities while adhering to a strict consistency notion. Unfortunately, their operation availabilities are strictly upper-bounded. Probabilistically relaxing the consistency notion permits to overcome this bound, introducing probabilistic data replication strategies that allow for a data consiste...

Reliability is one of the main salient assets of modern weapon systems. The estimation of the failure rate of the major subsystems of military defence systems is of utmost importance in the design of any country's overall defence system. The results of a study to estimate the failure rate of the main computer system of the launcher of a shore to sea missile launcher is presented in this study. ...

A metro control system is a software/hardware platform that provides automated mechanisms to enforce the safety of a metropolitan transportation system. In this field, the current technical trend is the Communications-based Train Control (CBTC) solution. CBTC platforms are characterized by a continuous wireless interaction between trains and ground controls. Several degrees of automation are pr...

During the last decade, a model based technique known as enterprise architecture has grown into an established approach for management of information systems in organizations. The use of enterprise architecture primarily promotes good decision-making and communication between business and IT stakeholders. This paper visualizes a scenario where enterprise architecture models are utilized to eval...

In this paper we quantitatively evaluate dependability/security of a computer-based system subject to Denial of Service (DoS) attacks. More specifically, we develop two semi-Markov models for describing the stochastic behavior of systems with different security patch release strategies. The optimal security patch management policies are then formulated and analytically derived to maximize the s...

Tandem computer systems are designed to be single-fault tolerant. This paper takes a census of customer system outages reported to Tandem. The census shows a clear improvement in the reliability of hardware and maintenance. It indicates that now (1989) software is the majority source of reported system outages (62%), followed by system operations (15%). This is a dramatic shift from the statist...

Motivated by the lack of rapid improvement in the availability of Internet server systems, we introduce a new philosophy for designing highly-available systems that better reflects the realities of the Internet service environment. Our approach, denoted repair-centric system design, is based on the belief that failures are inevitable in complex, human-administered systems, and thus we focus on ...

Farsite is a secure, scalable, distributed file system that logically functions as a centralized file server but that is physically realized on a set of client desktop computers. Farsite provides security, reliability, and availability by storing replicas of each file on multiple machines. It continuously monitors machine availability and relocates replicas as necessary to maximize the effectiv...