Find out why IT professionals are turning to CBT for its ability to enhance backup operations, providing a more efficient and effective data protection solution. To Know more: https://stonefly.com/white-papers/change-block-tracking-cbt/
SOLUTION MANUAL OF OPERATING SYSTEM CONCEPTS BY ABRAHAM SILBERSCHATZ, PETER B...vtunotesbysree
Here are three major complications that concurrent processing adds to an operating system:
1. Resource allocation and scheduling becomes more complex. The OS must allocate CPU time, memory, file descriptors, etc. among multiple concurrent processes and ensure all processes receive adequate resources. It must also schedule which process runs at what time on what CPU core.
2. Synchronization and communication between processes is more difficult. The OS must provide mechanisms for processes to synchronize their actions when accessing shared resources and to allow inter-process communication. This introduces challenges around things like race conditions and deadlocks.
3. Reliability and fault tolerance is harder. If one process crashes or hangs, it should not affect other processes. The OS must be able to
One of the requirements for mission critical systems is to provide reliable volume backup without impacting running system. The recommended way of cinder backup is to unmount volume before backup to avoid crash consistent backup. Unmounting is intrusive in nature and may not be feasible for mission critical systems.
This presentation focuses on strategy to achieve non-intrusive cinder backup. The presentation was given in Openstack summit at Sydney on 06 Nov 2017.
https://www.openstack.org/videos/sydney-2017/truly-non-intrusive-openstack-cinder-backup-for-mission-critical-systems
This document discusses answering Oracle technical interview questions. It begins by emphasizing the importance of also conveying personal details to interviewers. The document then provides sample questions and answers on various Oracle database administration topics. These include backups, recovery, initialization parameters, database objects, monitoring and troubleshooting, performance tuning, and directory structures. The responses are meant to demonstrate understanding rather than be definitive answers. A follow up document with additional questions is promised.
Garbage Collection, Tuning And Monitoring JVM In EBS 11i And R12sidg75
The document discusses garbage collection, tuning, and monitoring the Java Virtual Machine (JVM) in Oracle E-Business Suite 11i and R12. It begins by introducing garbage collection and its role in memory management. It then covers key garbage collection concepts like generations, collectors, and metrics for measurement. The document also lists some notable JVM parameters and provides guidance on monitoring the JVM. It concludes by mentioning future changes related to the JRockit JVM.
This document discusses prefetching and spooling as methods to overlap I/O operations with CPU operations to improve system performance. Prefetching involves initiating the next read operation after the current one completes, allowing the CPU and I/O device to work in parallel. Spooling overlaps the I/O of one job with the computation and output of other jobs by using a buffer. Spooling is generally more effective than prefetching at overlapping operations.
Renesas DevCon 2010: Starting a QT Application with Minimal Bootandrewmurraympc
The document discusses optimizing boot times for an embedded Linux application with QT by specializing Linux functionality. It describes analyzing boot processes to identify delays, removing unnecessary functionality, optimizing code, and reordering processes. These techniques were applied to a home automation case study, reducing boot time from 19.44 seconds to 0.77 seconds, a 96% decrease. Further optimization may be possible by better understanding QT delays and utilizing hardware acceleration.
How to put 10lbs of functionality into a 5lb package.Marc Karasek
The document discusses how to add more functionality to an embedded system without increasing the package size. It recommends layering the firmware code into platform-dependent, system-dependent, and OS/application layers. Each layer should be able to load the layer above it. It also suggests including robust debug capabilities to help troubleshoot problems early in the boot process using a small, lightweight debug monitor. Layering the code in this way allows for a modular debugging approach rather than a monolithic one.
SOLUTION MANUAL OF OPERATING SYSTEM CONCEPTS BY ABRAHAM SILBERSCHATZ, PETER B...vtunotesbysree
Here are three major complications that concurrent processing adds to an operating system:
1. Resource allocation and scheduling becomes more complex. The OS must allocate CPU time, memory, file descriptors, etc. among multiple concurrent processes and ensure all processes receive adequate resources. It must also schedule which process runs at what time on what CPU core.
2. Synchronization and communication between processes is more difficult. The OS must provide mechanisms for processes to synchronize their actions when accessing shared resources and to allow inter-process communication. This introduces challenges around things like race conditions and deadlocks.
3. Reliability and fault tolerance is harder. If one process crashes or hangs, it should not affect other processes. The OS must be able to
One of the requirements for mission critical systems is to provide reliable volume backup without impacting running system. The recommended way of cinder backup is to unmount volume before backup to avoid crash consistent backup. Unmounting is intrusive in nature and may not be feasible for mission critical systems.
This presentation focuses on strategy to achieve non-intrusive cinder backup. The presentation was given in Openstack summit at Sydney on 06 Nov 2017.
https://www.openstack.org/videos/sydney-2017/truly-non-intrusive-openstack-cinder-backup-for-mission-critical-systems
This document discusses answering Oracle technical interview questions. It begins by emphasizing the importance of also conveying personal details to interviewers. The document then provides sample questions and answers on various Oracle database administration topics. These include backups, recovery, initialization parameters, database objects, monitoring and troubleshooting, performance tuning, and directory structures. The responses are meant to demonstrate understanding rather than be definitive answers. A follow up document with additional questions is promised.
Garbage Collection, Tuning And Monitoring JVM In EBS 11i And R12sidg75
The document discusses garbage collection, tuning, and monitoring the Java Virtual Machine (JVM) in Oracle E-Business Suite 11i and R12. It begins by introducing garbage collection and its role in memory management. It then covers key garbage collection concepts like generations, collectors, and metrics for measurement. The document also lists some notable JVM parameters and provides guidance on monitoring the JVM. It concludes by mentioning future changes related to the JRockit JVM.
This document discusses prefetching and spooling as methods to overlap I/O operations with CPU operations to improve system performance. Prefetching involves initiating the next read operation after the current one completes, allowing the CPU and I/O device to work in parallel. Spooling overlaps the I/O of one job with the computation and output of other jobs by using a buffer. Spooling is generally more effective than prefetching at overlapping operations.
Renesas DevCon 2010: Starting a QT Application with Minimal Bootandrewmurraympc
The document discusses optimizing boot times for an embedded Linux application with QT by specializing Linux functionality. It describes analyzing boot processes to identify delays, removing unnecessary functionality, optimizing code, and reordering processes. These techniques were applied to a home automation case study, reducing boot time from 19.44 seconds to 0.77 seconds, a 96% decrease. Further optimization may be possible by better understanding QT delays and utilizing hardware acceleration.
How to put 10lbs of functionality into a 5lb package.Marc Karasek
The document discusses how to add more functionality to an embedded system without increasing the package size. It recommends layering the firmware code into platform-dependent, system-dependent, and OS/application layers. Each layer should be able to load the layer above it. It also suggests including robust debug capabilities to help troubleshoot problems early in the boot process using a small, lightweight debug monitor. Layering the code in this way allows for a modular debugging approach rather than a monolithic one.
Questions Log: Dynamic Cubes – Set to Retire Transformer?Senturus
This document contains a questions log from a webinar about optimizing Cognos performance. It includes questions from webinar attendees about topics like using virtual cubes and dynamic cubes to address large data volumes, optimizing in-memory aggregates, hardware sizing requirements for dynamic cubes, and configuration considerations when using dynamic cubes. The questions are answered in detail to help attendees understand how to best implement and optimize dynamic cubes in Cognos.
Workshop - The Little Pattern That Could.pdfTobiasGoeschel
The document discusses refactoring a monolithic application to follow Domain-Driven Design (DDD) and microservice principles. It provides exercises and hints to guide refactoring the codebase to use Hexagonal Architecture with separated domains, commands and queries using CQRS, and persistence-oriented repositories. Later exercises discuss improving test speed by isolating dependencies and refactoring for a serverless architecture by splitting the application into individual use cases and replacing the in-memory repository.
RxJava pour Android : présentation lors du GDG Android MontréalSidereo
Reactive extensions are a framework created by Microsoft for .NET at the end of 2009.
It is a «library that allows programmers to write succinct declarative code to orchestrate and coordinate asynchronous and event-based programs »
The way you write code with this library might be referred to as functional reactive programming, we’ll talk more about this during the presentation.
It is now available for Java and Android. The specifics for Android are helpers for thread and UI stuff.
Jake Wharton is a huge contributor for the Android version
Redo logs are transaction logs that Oracle uses for recovery purposes. They allow Oracle to restore data to its state before a failure by replaying redo records. There are two types of redo logs: online redo logs which are used circularly for current transactions, and archived redo logs which are used to restore data during recovery. A COMMIT makes changes permanent by writing redo records to the online logs, while a ROLLBACK undoes changes by reading from the rollback segments to reverse operations. Temporary tables generate minimal redo since their changes are not recoverable, while changes to permanent tables generate standard redo logging.
Analyze a SVC, STORWIZE metro/ global mirror performance problem-v58-20150818...Michael Pirker
Latency problem was reported for VDisk CA-CL1-Disk04-N at 02/05/15 8:09,
The environment are two clusters connected with Metro Mirror. The first aim of this document is to show how we found the root cause of this problem in the link between the two clusters.
The second aim of this document is to describe how the root cause for this problem was found by using the BVQ structured performance problem analysis method. It demonstrates that successful analysis work needs a structured method and also a tool which supports this method and delivers the needed technical insight. We have the concept that everybody should be able to conduct a performance analysis. This is important because the level of service is lowered day by day and especially small customers are more and more reliant on their own skills or on the skills of their partners. This is a common problem occurring at all vendors!
A practical look at how to build & run IoT business logicVeselin Pizurica
Automation is what takes IoT projects further than visualisation dashboards and offline analysis into real-world actions that drive results. Rule engines are automation frameworks that enable companies to accelerate application development and support the complexity and scale that IoT automation requires.
We will have a practical look at how you can evaluate any rules engine by immediately matching your unique business logic requirements with the necessary rules engine capabilities.
The document discusses monitors, which are a synchronization mechanism used in operating systems. A monitor is a collection of shared variables and associated procedures that enforce mutual exclusion. Only one process can be active in a monitor at a time. Monitors were developed to make it easier to avoid deadlocks compared to other synchronization methods like semaphores. The document provides examples of how monitors can be used to solve common synchronization problems.
IRJET- A Futuristic Cache Replacement using Hybrid RegressionIRJET Journal
This document presents a new cache replacement algorithm called Hybrid Regression that aims to improve cache hit rates. It summarizes existing cache replacement algorithms like LRU, FIFO, Hawkeye/PA-Hawkeye, and SHiP. It then describes the proposed Hybrid Regression algorithm, which uses parameters like memory region, instruction PC, and instruction sequence to predict entries that should be cached. Simulation results show the Hybrid Regression approach improves hit rates over LRU and FIFO algorithms by 251% and 279% respectively when tested on random data. The algorithm provides a potential improvement over traditional cache replacement methods but has challenges in obtaining real usage data for evaluation.
BNFO-501/.DS_Store
__MACOSX/BNFO-501/._.DS_Store
BNFO-501/BNFO501 Course Guide.pdf
1
Bioinformatics 501
2
Table of Contents
Course Outline ................................................................................................................................ 3
Chapter 1: Physical Level ............................................................................................................... 7
Chapter 2: Algorithm Complexity ................................................................................................ 16
Chapter 3: Search Algorithms ....................................................................................................... 22
Chapter 4: Sort Algorithms ........................................................................................................... 28
Chapter 5: Trees ............................................................................................................................ 43
Chapter 6: Hashing ....................................................................................................................... 62
Authors’ Notes .............................................................................................................................. 66
3
Course Outline
Purpose
The purpose of this document is to introduce students to concepts, structures and
algorithms that form a foundation on which a database is built. Since this is created for a
specific class we will assume students have at least taken CMSC-256 at VCU or an equivalent
course.
Format
Consistency will be a key element in learning and understanding this material, but
unfortunately there can be many different ways to format this material. We will use this section
to illustrate different formats we will use in the examples of this text.
We are assuming the readers of this text to have some general understanding of
programming and our target audience is supposed to have some background specifically in
Java. We will use a pseudo code in our examples that can easily be translated to Java code, but
can also be applied to many other languages. An example piece of code is below followed by
the Java implementation.
Pseudo Code
Java implementation
4
Structure
This chapter will briefly introduce what will be covered in this document. We will cover:
• Computer Architecture (Physical Level)
• Algorithm Complexity
• Search Algorithms
• Sort Algorithms
• Trees
• Hashing
Chapter 1: The Physical Level
While we can assume you have taken at least an intermediate Java course, we cannot
assume you have taken any courses on computer architecture. The first section will briefly
cover key concepts in this field that you will surely hear again in a Database course.
You will learn about how information is stored in a computer in both temporary and
long term storage along with the time it takes to set and receive information from ...
The Flying Circus is an Operations-as-a-Service platform that supports project development teams to run their custom-develop software for clients. Earlier in 2014 we experienced a major data loss and had to perform massive disaster recovery. Unfortunately our Bacula setup was not up to the task and it took us longer and more effort to restore the data than we and our customers expected.
In this case study I’d like to present our public and very honest root cause analysis on how we managed to lose a lot of VMs’ data, how the restore happened, what we learned and how we’re trying to get better. After investigating our options for the future we decided to move away from Bacula’s file and VTL-oriented model and are currently implementing a solution based on CoW-filesystems (ZFS/btrfs), block-layer snapshots and diffing, and a small utility to glue things together.
Rational Team Concert (RTC) is an IBM tool for software development team collaboration. It provides an environment for managing plans, tasks, source control, documents, builds, and reports. RTC is highly customizable and built on the IBM Jazz platform. It allows teams to search for items, extract work items from descriptions, view component histories, annotate files, change work item attributes in bulk, and more.
Infrastructure as Code (IaC), how to choose the right tool, terraform vs. CDK vs. Pulumi, best practices, Principles, and a lot of the underlying principles are described in this crash course.
Twan Koot - Beyond the % usage, an in-depth look into monitoringNeotys_Partner
Since its beginning, the Performance Advisory Council aims to promote engagement between various experts from around the world, to create relevant, value-added content sharing between members. For Neotys, to strengthen our position as a thought leader in load & performance testing. During this event, 12 participants convened in Chamonix (France) exploring several topics on the minds of today’s performance tester such as DevOps, Shift Left/Right, Test Automation, Blockchain and Artificial Intelligence.
This document provides a two-page report on considering Frame Relay as a connectivity option between the Pittsburgh and Cleveland offices. It compares Frame Relay to other WAN technologies like ATM and dedicated leased lines. Frame Relay is presented as a cost-effective option that provides connectivity through virtual circuits while only paying for the bandwidth used. Other options are discussed but Frame Relay is ultimately recommended as the best fit for the needs of this project.
The document discusses different tools for analyzing iOS code for bugs and performance issues. It describes the static analyzer as the first line of defense, which finds logic flaws and coding issues by analyzing code similar to a compiler. It then discusses using the Instruments tool on the simulator as the second line of defense for finding memory leaks and performance bottlenecks. Specific Instruments like Allocations, Leaks, and Time Profiler are described for analyzing different types of issues. Command line tools for configuring which static analyzer version is used are also overviewed.
The document discusses key concepts in computer architecture including Amdahl's law for predicting speedup from parallelization, branch predictors for improving instruction flow, cache organization and types, hazards that can occur in pipelines, interrupts for responding to events, and jump instructions for breaking standard instruction flow. It provides simplified explanations of these concepts in an accessible way for learning purposes.
The document discusses key concepts in computer architecture including Amdahl's law for predicting speedup from parallelization, branch predictors for improving instruction flow, cache organization and types, hazards that can occur in pipelines, interrupts for responding to events, and jump instructions for breaking standard instruction flow. It provides simplified explanations of these concepts in an accessible way for learning purposes.
This document discusses approaches for improving Django performance. It notes that front-end performance issues typically account for 80-90% of response time and recommends caching static assets, bundling/minifying assets, and using a CDN. For back-end issues, it recommends profiling views to identify SQL or Python bottlenecks and provides techniques like select_related, prefetch_related, and caching to address different problem areas. The key message is that performance work requires understanding where time is actually being spent before applying optimizations.
@SIMUL8 Virtual User Group, September: Brian Harrington, Less is MoreSIMUL8 Corporation
@SIMUL8 Virtual User Group
We know not everyone can take time out to attend conferences and user meetings, so we're making it easy for you to get involved with our series of virtual user groups.
Learning Zone:
Brian Harrington will call on his experience as a Six Sigma Black Belt Black Belt to share his thoughts on "A Six Sigma approach to building successful simulations.
Observability: Beyond the Three Pillars with SpringVMware Tanzu
In this presentation, we’ll explore the basics of the three pillars and what Spring has to offer to implement them for logging (SLF4J), metrics (Micrometer), and distributed tracing (Spring Cloud Sleuth, Zipkin/Brave, OpenTelemetry).
I’ll also talk about how to take your system to the next level, and what else you can find in Spring and related technologies to look under the hood of your running system (Spring Boot Actuator, Logbook, Eureka, Spring Boot Admin, Swagger, Spring HATEOAS) and what our future plans are.
Veeam Replication in Azure Cloud: Ensuring Business Continuity and Data Prote...MaryJWilliams2
Explore how Veeam replication in Azure Cloud can provide robust data protection and business continuity for your organization. This guide delves into the advantages of using Veeam for replicating data to Azure, including enhanced disaster recovery capabilities, seamless integration, and cost-effective scalability. To Know more: https://stonefly.com/white-papers/a-guide-to-veeam-replication-in-azure-cloud/
Eyes Everywhere: The Power of Body-Worn and Dashboard CamerasMaryJWilliams2
Explore the dual perspective of surveillance with body-worn and dashboard cameras, delving into their roles in enhancing safety, accountability, and transparency across various industries. Discover how these cameras revolutionize monitoring and documentation in real-time scenarios. To Know more: https://stonefly.com/white-papers/cost-effective-storage-for-body-worn-and-dashboard-camera/
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This document contains a questions log from a webinar about optimizing Cognos performance. It includes questions from webinar attendees about topics like using virtual cubes and dynamic cubes to address large data volumes, optimizing in-memory aggregates, hardware sizing requirements for dynamic cubes, and configuration considerations when using dynamic cubes. The questions are answered in detail to help attendees understand how to best implement and optimize dynamic cubes in Cognos.
Workshop - The Little Pattern That Could.pdfTobiasGoeschel
The document discusses refactoring a monolithic application to follow Domain-Driven Design (DDD) and microservice principles. It provides exercises and hints to guide refactoring the codebase to use Hexagonal Architecture with separated domains, commands and queries using CQRS, and persistence-oriented repositories. Later exercises discuss improving test speed by isolating dependencies and refactoring for a serverless architecture by splitting the application into individual use cases and replacing the in-memory repository.
RxJava pour Android : présentation lors du GDG Android MontréalSidereo
Reactive extensions are a framework created by Microsoft for .NET at the end of 2009.
It is a «library that allows programmers to write succinct declarative code to orchestrate and coordinate asynchronous and event-based programs »
The way you write code with this library might be referred to as functional reactive programming, we’ll talk more about this during the presentation.
It is now available for Java and Android. The specifics for Android are helpers for thread and UI stuff.
Jake Wharton is a huge contributor for the Android version
Redo logs are transaction logs that Oracle uses for recovery purposes. They allow Oracle to restore data to its state before a failure by replaying redo records. There are two types of redo logs: online redo logs which are used circularly for current transactions, and archived redo logs which are used to restore data during recovery. A COMMIT makes changes permanent by writing redo records to the online logs, while a ROLLBACK undoes changes by reading from the rollback segments to reverse operations. Temporary tables generate minimal redo since their changes are not recoverable, while changes to permanent tables generate standard redo logging.
Analyze a SVC, STORWIZE metro/ global mirror performance problem-v58-20150818...Michael Pirker
Latency problem was reported for VDisk CA-CL1-Disk04-N at 02/05/15 8:09,
The environment are two clusters connected with Metro Mirror. The first aim of this document is to show how we found the root cause of this problem in the link between the two clusters.
The second aim of this document is to describe how the root cause for this problem was found by using the BVQ structured performance problem analysis method. It demonstrates that successful analysis work needs a structured method and also a tool which supports this method and delivers the needed technical insight. We have the concept that everybody should be able to conduct a performance analysis. This is important because the level of service is lowered day by day and especially small customers are more and more reliant on their own skills or on the skills of their partners. This is a common problem occurring at all vendors!
A practical look at how to build & run IoT business logicVeselin Pizurica
Automation is what takes IoT projects further than visualisation dashboards and offline analysis into real-world actions that drive results. Rule engines are automation frameworks that enable companies to accelerate application development and support the complexity and scale that IoT automation requires.
We will have a practical look at how you can evaluate any rules engine by immediately matching your unique business logic requirements with the necessary rules engine capabilities.
The document discusses monitors, which are a synchronization mechanism used in operating systems. A monitor is a collection of shared variables and associated procedures that enforce mutual exclusion. Only one process can be active in a monitor at a time. Monitors were developed to make it easier to avoid deadlocks compared to other synchronization methods like semaphores. The document provides examples of how monitors can be used to solve common synchronization problems.
IRJET- A Futuristic Cache Replacement using Hybrid RegressionIRJET Journal
This document presents a new cache replacement algorithm called Hybrid Regression that aims to improve cache hit rates. It summarizes existing cache replacement algorithms like LRU, FIFO, Hawkeye/PA-Hawkeye, and SHiP. It then describes the proposed Hybrid Regression algorithm, which uses parameters like memory region, instruction PC, and instruction sequence to predict entries that should be cached. Simulation results show the Hybrid Regression approach improves hit rates over LRU and FIFO algorithms by 251% and 279% respectively when tested on random data. The algorithm provides a potential improvement over traditional cache replacement methods but has challenges in obtaining real usage data for evaluation.
BNFO-501/.DS_Store
__MACOSX/BNFO-501/._.DS_Store
BNFO-501/BNFO501 Course Guide.pdf
1
Bioinformatics 501
2
Table of Contents
Course Outline ................................................................................................................................ 3
Chapter 1: Physical Level ............................................................................................................... 7
Chapter 2: Algorithm Complexity ................................................................................................ 16
Chapter 3: Search Algorithms ....................................................................................................... 22
Chapter 4: Sort Algorithms ........................................................................................................... 28
Chapter 5: Trees ............................................................................................................................ 43
Chapter 6: Hashing ....................................................................................................................... 62
Authors’ Notes .............................................................................................................................. 66
3
Course Outline
Purpose
The purpose of this document is to introduce students to concepts, structures and
algorithms that form a foundation on which a database is built. Since this is created for a
specific class we will assume students have at least taken CMSC-256 at VCU or an equivalent
course.
Format
Consistency will be a key element in learning and understanding this material, but
unfortunately there can be many different ways to format this material. We will use this section
to illustrate different formats we will use in the examples of this text.
We are assuming the readers of this text to have some general understanding of
programming and our target audience is supposed to have some background specifically in
Java. We will use a pseudo code in our examples that can easily be translated to Java code, but
can also be applied to many other languages. An example piece of code is below followed by
the Java implementation.
Pseudo Code
Java implementation
4
Structure
This chapter will briefly introduce what will be covered in this document. We will cover:
• Computer Architecture (Physical Level)
• Algorithm Complexity
• Search Algorithms
• Sort Algorithms
• Trees
• Hashing
Chapter 1: The Physical Level
While we can assume you have taken at least an intermediate Java course, we cannot
assume you have taken any courses on computer architecture. The first section will briefly
cover key concepts in this field that you will surely hear again in a Database course.
You will learn about how information is stored in a computer in both temporary and
long term storage along with the time it takes to set and receive information from ...
The Flying Circus is an Operations-as-a-Service platform that supports project development teams to run their custom-develop software for clients. Earlier in 2014 we experienced a major data loss and had to perform massive disaster recovery. Unfortunately our Bacula setup was not up to the task and it took us longer and more effort to restore the data than we and our customers expected.
In this case study I’d like to present our public and very honest root cause analysis on how we managed to lose a lot of VMs’ data, how the restore happened, what we learned and how we’re trying to get better. After investigating our options for the future we decided to move away from Bacula’s file and VTL-oriented model and are currently implementing a solution based on CoW-filesystems (ZFS/btrfs), block-layer snapshots and diffing, and a small utility to glue things together.
Rational Team Concert (RTC) is an IBM tool for software development team collaboration. It provides an environment for managing plans, tasks, source control, documents, builds, and reports. RTC is highly customizable and built on the IBM Jazz platform. It allows teams to search for items, extract work items from descriptions, view component histories, annotate files, change work item attributes in bulk, and more.
Infrastructure as Code (IaC), how to choose the right tool, terraform vs. CDK vs. Pulumi, best practices, Principles, and a lot of the underlying principles are described in this crash course.
Twan Koot - Beyond the % usage, an in-depth look into monitoringNeotys_Partner
Since its beginning, the Performance Advisory Council aims to promote engagement between various experts from around the world, to create relevant, value-added content sharing between members. For Neotys, to strengthen our position as a thought leader in load & performance testing. During this event, 12 participants convened in Chamonix (France) exploring several topics on the minds of today’s performance tester such as DevOps, Shift Left/Right, Test Automation, Blockchain and Artificial Intelligence.
This document provides a two-page report on considering Frame Relay as a connectivity option between the Pittsburgh and Cleveland offices. It compares Frame Relay to other WAN technologies like ATM and dedicated leased lines. Frame Relay is presented as a cost-effective option that provides connectivity through virtual circuits while only paying for the bandwidth used. Other options are discussed but Frame Relay is ultimately recommended as the best fit for the needs of this project.
The document discusses different tools for analyzing iOS code for bugs and performance issues. It describes the static analyzer as the first line of defense, which finds logic flaws and coding issues by analyzing code similar to a compiler. It then discusses using the Instruments tool on the simulator as the second line of defense for finding memory leaks and performance bottlenecks. Specific Instruments like Allocations, Leaks, and Time Profiler are described for analyzing different types of issues. Command line tools for configuring which static analyzer version is used are also overviewed.
The document discusses key concepts in computer architecture including Amdahl's law for predicting speedup from parallelization, branch predictors for improving instruction flow, cache organization and types, hazards that can occur in pipelines, interrupts for responding to events, and jump instructions for breaking standard instruction flow. It provides simplified explanations of these concepts in an accessible way for learning purposes.
The document discusses key concepts in computer architecture including Amdahl's law for predicting speedup from parallelization, branch predictors for improving instruction flow, cache organization and types, hazards that can occur in pipelines, interrupts for responding to events, and jump instructions for breaking standard instruction flow. It provides simplified explanations of these concepts in an accessible way for learning purposes.
This document discusses approaches for improving Django performance. It notes that front-end performance issues typically account for 80-90% of response time and recommends caching static assets, bundling/minifying assets, and using a CDN. For back-end issues, it recommends profiling views to identify SQL or Python bottlenecks and provides techniques like select_related, prefetch_related, and caching to address different problem areas. The key message is that performance work requires understanding where time is actually being spent before applying optimizations.
@SIMUL8 Virtual User Group, September: Brian Harrington, Less is MoreSIMUL8 Corporation
@SIMUL8 Virtual User Group
We know not everyone can take time out to attend conferences and user meetings, so we're making it easy for you to get involved with our series of virtual user groups.
Learning Zone:
Brian Harrington will call on his experience as a Six Sigma Black Belt Black Belt to share his thoughts on "A Six Sigma approach to building successful simulations.
Observability: Beyond the Three Pillars with SpringVMware Tanzu
In this presentation, we’ll explore the basics of the three pillars and what Spring has to offer to implement them for logging (SLF4J), metrics (Micrometer), and distributed tracing (Spring Cloud Sleuth, Zipkin/Brave, OpenTelemetry).
I’ll also talk about how to take your system to the next level, and what else you can find in Spring and related technologies to look under the hood of your running system (Spring Boot Actuator, Logbook, Eureka, Spring Boot Admin, Swagger, Spring HATEOAS) and what our future plans are.
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5th Power Grid Model Meet-up
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Power Grid Model
The global energy transition is placing new and unprecedented demands on Distribution System Operators (DSOs). Alongside upgrades to grid capacity, processes such as digitization, capacity optimization, and congestion management are becoming vital for delivering reliable services.
Power Grid Model is an open source project from Linux Foundation Energy and provides a calculation engine that is increasingly essential for DSOs. It offers a standards-based foundation enabling real-time power systems analysis, simulations of electrical power grids, and sophisticated what-if analysis. In addition, it enables in-depth studies and analysis of the electrical power grid’s behavior and performance. This comprehensive model incorporates essential factors such as power generation capacity, electrical losses, voltage levels, power flows, and system stability.
Power Grid Model is currently being applied in a wide variety of use cases, including grid planning, expansion, reliability, and congestion studies. It can also help in analyzing the impact of renewable energy integration, assessing the effects of disturbances or faults, and developing strategies for grid control and optimization.
What to expect
For the upcoming meetup we are organizing, we have an exciting lineup of activities planned:
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Attributes & automation parameters enable the automation author to pass data values from one automation component to the next. During this webinar, our FME Flow Specialists will cover leveraging the three types of these output attributes & parameters in FME Flow: Event, Custom, and Automation. As a bonus, they’ll also be making use of the Split-Merge Block functionality.
You’ll leave this webinar with a better understanding of how to maximize the potential of automations by making use of attributes & automation parameters, with the ultimate goal of setting your enterprise integration workflows up on autopilot.
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Join us to learn how UiPath Apps can directly and easily interact with prebuilt connectors via Integration Service--including Salesforce, ServiceNow, Open GenAI, and more.
The best part is you can achieve this without building a custom workflow! Say goodbye to the hassle of using separate automations to call APIs. By seamlessly integrating within App Studio, you can now easily streamline your workflow, while gaining direct access to our Connector Catalog of popular applications.
We’ll discuss and demo the benefits of UiPath Apps and connectors including:
Creating a compelling user experience for any software, without the limitations of APIs.
Accelerating the app creation process, saving time and effort
Enjoying high-performance CRUD (create, read, update, delete) operations, for
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Speakers:
Russell Alfeche, Technology Leader, RPA at qBotic and UiPath MVP
Charlie Greenberg, host
2. Absract
Change Block Tracking or Change Tracking or CBT is making a record or journal of
which blocks of a storage object were changed by I/O. A storage object is any logical-
ly contiguous space used for storage of data.
Now you need to keep in mind that CBT doesn’t keep track of what data was written,
it only logs which areas of the object were written. Such track can be used for various
applications, primarily for backup and restore. Usually such tracking is used to know
what blocks have changed during a given time frame.
1
CBT : A Technical Review
3. Backup uses snapshot technologies? So where does CBT come in
all of this?
Backup technologies rely on snapshot to make the backup consistent, however it’s
very tedious to take backups of the entire object at every backup cycle. So what you
do is either you use incremental or differential snapshots.
Using incremental snapshots, one can know what has changed between two snap-
shots. Backup applications use this information to know what blocks of the object to
backup. Let’s look at the following example of backup using snapshots.
2
At the first backup cycle, we take a snapshot of the device and we take a full backup
using the snapshot. At the next backup cycle we take an incremental snapshot of the
device. This snapshot logic is already provided by the block title. Next we calculate
what has changed between the two snapshots and take the backup of only those
CBT : A Technical Review
4. We can notice here that:
1) The snapshot has to exist not only for the period of backup, but for over two
backup cycles. It needs to exist for more than two backup cycles.
2) Production I/O has always the need to go through this snapshot layer. Meaning
that if you have the snapshot in the I/O path, then every I/O that you do may translate
into more than one read/write based on the type of the snapshot.
3) These snapshots have to live for the longer time and the size of the snapshot will
keep growing as much as you do I/O to it. When you want to delete the snapshot, it
will be time consuming and tedious because these snapshots are so large that it
takes time to manage all the data in the snapshot areas.
The effect of point no. 2&3 is that they are multiplied when the backup interval is
large. Imagine that your backup interval is read/write, now in case of redirect on write
snapshots it would mean that you are merging the entire reads of data from the data
area onto the base device.
3
CBT : A Technical Review
Will all these points degrade the performance of the produc�on
system?
That’s true and it’s actually one of the problems that needs to be solved. Backup
applications used to relay on snapshots to know what has changed but CBT provides
them with information out of band. These backup applications don’t need to keep
the snapshots alive after the backup is complete.
5. To take a backup you need to know what has changed between two snapshots,
otherwise you need to keep taking full backup every time, but for this to happen a
new tracking instant has to be started atomically at the creation of the snapshot.
However changing or integrating with the existing snapshot technology is difficult
and is something that’s not necessary.
This problem is easily solved by using two simultaneous tracking instances that over-
lap across the snapshot creation operation.
How Backup with CBT works
4
CBT : A Technical Review
For Example this is the timeline that is given here as shown in the graph. Starting
from left to right, you first start tracking the instance “T1-0” and you take a snapshot
(S-0) of the device followed by a full backup. You always start with a full backup. As
soon as your backup is done you delete the snapshot. This is because you already
have a tracking out of band in place.
6. In the next backup cycle, which is maybe a day later, a month, a week, or else, you
start another tracking instance which is let’s say “TI-1” and then you follow it with
another snapshot (S-1). Now after taking the snapshot you stop tracking instance
“TI-0” which you have started a week before. Now the tracking instance TI-0 has all
changes that has happened to that storage object in that particular week.
You use that instance “TI-0” to take an incremental backup, so backup has to know
which blocks have changed so it can just read that information and take the backup.
Once your backup is complete, you do not need that particular snapshot anymore.
You can see that the snapshot only exists till the time the backup needs it and it
doesn’t need to live anymore. Essentially there are no incremental snapshots, there’s
just one snapshot alive that you need for each backup.
5
CBT : A Technical Review
Components that encompass the CBT
There are two major components that are required for CBT:
1) The hook or the filter. What we mean by hook is something that allows you
to take a peek at the I/O on the storage object. Whenever an application to the I/O to
that particular storage object, you need to know which block of the storage object it’s
touching.
The most important requirement for such a hook is that it has to be fast, why?
Because the problem that we are trying to solve by using CBT is to lessen the delay
on the I/O in case of snapshots, and the same needs to hold to here. This is actually
easily solved if you know you have an intermediate fast cache that’s available there
for the hook to record all the tracking. This tracking Data can be asynchronously
returned to Persistent Record later. Also the hook isn’t concerned with whether the
I/O is successful or not.
7. 6
CBT : A Technical Review
2) Persistent Record. It’s not necessary that you have this record on disk, it can
be in memory record as well or it can be something like a map disk cover. The format
of this persistent record should be in such a way that it’s easily consumable. For
instance you have various formats, you have a lock structured format where the track-
ing data is appended to the end of the record. However it may result in more burden.
For example to know what has changed between a given time frame you need to go
to the entire log to figure out the areas. VMware uses such a structure because it uses
CTK file. Another format of Persistent Record is bitmap which images every bit it
represents and logical extent of the storage object. Built bit is set if the logical extent
is partially or fully return. If the logical extent is 256 kb even if you write 4 kb of that
particular extent, the block is considered as return. This essentially avoids having
large bitmap sizes. A multiple bitmap can represent multiple tracking instances, so
it’s relatively easy to consume.
Can opera�ons like merging of bitmaps be performed?
Merging of bitmaps is another operation that can be performed. If you have one
tracking instance represented by bitmap and another tracking instance represented
by another bitmap, and you want to know what data has changed across both
instances, you just need to merge the data and you get the needed data.
Things to keep in mind when designing CBT
One of the most important components of CBT is the hook or filter. And the problem
that needs solving is performance degradation in production I/O. The hook has to be
fast enough so as to not degrade the I/O performance. Most important than that it
has to capture all the I/O paths. You can never miss tracking one I/O path to that
particular block, or device or storage object because if you do the tracking data
becomes inconsistent, and it results in a corrupted backup. Moreover, the corruption
8. 7
CBT : A Technical Review
message will appear during restore, which is much later in the time frame. You won’t
know that during backup, it’s only during the restore and you don’t want that hap-
pening.
Scenarios that come into play with CBT
Some key scenarios that come into mind is during identification of the storage
object. Basically your backup application and your tracking filter or the tracking soft-
ware, they have to be in consensus on how to identify storage object. It’s simple. For
instance if you are tracking SAN (Storage Area Network) devices then SCSI (Small
Computer System Interface) ID is one identifier.
Another Scenario is reboot. Sometimes a device is accessible in an early stage of the
boot. If you are tracking that device, and since one of our goals is not to miss any I/O,
your tracking filter or hook needs to be in place before that. Also during shutdown no
writes or I/O should be missed. If you are unable to capture or track all the I/O’s
during shutdown and boot, you take a full backup and you start a new tracking
instance.
Another scenario is device being renamed. Of course if you’re using the unique iden-
tifier you’re not in so much of trouble. Linux also allows for the storage object to be
offline and come back online as a separate device. CBT needs to know that device it
was tracking is now coming up as a separate name.