Strider: a black-box, state-based approach to change and configuration management and support

AbstractWe describe a new approach, called Strider, to Change and Configuration Management and Support (CCMS). Strider is a black-box approach: without relying on specifications, it uses state differencing to identify potential causes of differing program behaviors, uses state tracing to identify actual, run-time state dependencies, and uses statistical behavior modeling for noise filtering. Strider is a state-based approach: instead of linking vague, high level descriptions and symptoms to relevant actions, it models management and support problems in terms of individual, named pieces of low level configuration state and provides precise mappings to user-friendly information through a computer genomics database. We use troubleshooting of configuration failures to demonstrate that the Strider approach reduces problem complexity by several orders of magnitude, making root-cause analysis possible

Optimization strategies for large scale distributed systems

Every day we rely on large distributed software services for communication, information, commerce, entertainment, and many other personal and business use cases. These services are globally available, sometimes with billions of users. A single service may use hundreds of thousands of interconnected servers running in datacenters around the world to ensure it is both highly available and able to provide users with sub-second responses. Operating such a service costs hundreds of millions of dollars annually and typically requires thousands of engineers working on millions of lines of software to maintain and evolve it. The scale and complexity of these systems make their optimization difficult, however, it is vital that they operate as efficiently as possible given the costs involved. This thesis focuses on two of the most impactful optimization opportunities common to these systems: minimizing their resource allocations, and minimizing the time taken to resolve request attributes into processing parameters. This work was done in conjunction with one of the largest global commercial services to show the effectiveness of the techniques on real-world systems. First, we focus on capacity planning, which has significant business and environmental impact. More than 1% (292 TWh) of global electricity is currently consumed by datacenters and that amount continues to increase. The challenge here is to determine resource needs for unexpected usage increases or failures in addition to steady-state activity. The goal is to reduce over-provisioning without impacting any service guarantees. This thesis presents a significant improvement of the state-of-the-art via a new iterative black-box capacity planning model relying only on the relationships between workload, utilization, and quality. Collaborating with one of the largest global service owners, we enabled capacity reductions between 20% and 40% saving $50,000,000 USD annually. A global datacenter usage reduction at this scale would save enough electricity to offset the annual consumption of 44 million people in the UK – eliminating 34 billion tonnes of CO₂ emissions. Second, we focus on improving the request latency by optimizing a common component across all services – resolving request attributes into processing settings. We describe a technique for translating tabular data into code and compiling it into a binary index for point look-ups on sparse data-sets. Query performance of a large commercial service improved by 58 times compared to R-tree based solutions and O(10⁸) with commercial databases. Additionally, a new compiler optimization is introduced for addressing large blocks of conditional evaluations, motivated by observing that up to 70% of all processing time is consumed by 10% or less of the requests. Machine learning was shown to be effective at guiding the compiler towards the most efficient optimization to use for blocks of conditional evaluations, resulting in a 92 times reduction in average latency

Verbowski - Edmonton Food Security Dialogue presentation - April 2014 (annex 18g)

Presentation at the 2014 Edmonton Food Security Dialogue, focusing on the challenges of analyzing 24‐hour dietary recalls in Cambodia, partially based on experience from the Fish on Farms baseline survey

The effect of plant-based homestead food production with and without small-scale aquaculture on dietary intake of women farmers and their children in Prey Veng, Cambodia

In 2011-2013, 15.4% of the Cambodian population was undernourished, compared to <5% in Canada. The Cambodian diet is rice-based and low in nutrient-dense animal-source foods. Homestead food production (HFP) and aquaculture are potential interventions to improve dietary intake. However, we lack comprehensive evidence that these interventions improve intake. Using a cluster randomized control trial, I aimed to determine whether women and children receiving HFP with or without aquaculture have higher intakes or lower prevalence of inadequate intakes of select nutrients, compared to controls in Prey Veng, Cambodia. Ninety villages of ten households each (n=900) were randomized to: HFP, HFP plus aquaculture, or control. After 22-months of intervention, interviewers collected 24-hour dietary recalls (24HRs) from women 18-50 y (n=429) and children 6 m-7 y (n=421). Repeat 24HRs were collected (n=139) to allow for adjustment of within-person variation in intake (using PC-SIDE software). Mean nutrient intakes were compared using generalized estimating equations (GEE) models. Prevalence of nutrient inadequacy was compared by applying the Estimated Average Requirement cut-point method or probability approach and using GEE models. After intervention, women in the HFP group had higher mean intakes of zinc (+1.0 mg) and vitamin A (+139 Retinol Activity Equivalent (RAE)), compared to controls (p<0.05). Women in the HFP plus aquaculture group had higher mean intakes of vitamin A (+191 RAE) and iron (+2.7 mg), and lower prevalence of inadequate vitamin A intake (-19%) and iron intake at 10% bioavailability (-7%) and 5% bioavailability (-2%) levels, compared to controls (p<0.05). Among groups of children and between the HFP and HFP plus aquaculture groups for both women and children, there were no significant differences in nutrient intakes or prevalence of nutrient inadequacy. This research provides evidence that intervention with HFP in Cambodia results in higher zinc and vitamin A intakes, and intervention with HFP plus aquaculture results in higher vitamin A and iron intakes and reduced prevalence of inadequate vitamin A and iron intakes among women, compared to controls. Future research should assess the impact of these changes on clinical outcomes, the effect of seasonal changes on intake, and the feeding relationship between women and children.Land and Food Systems, Faculty ofGraduat

Daniels: Strider Typo-Patrol: Discovery and Analysis of Systematic Typo-Squatting. Microsoft Research

Typo-squatting refers to the practice of registering domain names that are typo variations of popular websites. We propose a new approach, called Strider Typo-Patrol, to discover large-scale, systematic typosquatters. We show that a large number of typosquatting domains are active and a large percentage of them are parked with a handful of major domain parking services, which serve syndicated advertisements on these domains. We also describe the Strider URL Tracer, a tool that we have released to allow website owners to systematically monitor typo-squatting domains of their sites. 1