This document discusses VMFS, the virtual machine file system used by VMware ESX. It covers:
- The design goals of VMFS, which are to minimize metadata overhead, provide high VM IO performance similar to raw devices, and help VMs handle transient and non-transient SAN errors.
- The architecture of VMFS, which uses clustered locks, resources, system files, and journaling to manage access across ESX servers sharing SAN storage.
- How VMFS adapts to SAN environments using techniques like optimistic locking, adaptive IO retries, data mover cloning, and directive SCSI commands.
- The conclusion restates that VMFS is designed for
Unix and shell programming | Unix File System | Unix File Permission | BlocksLOKESH KUMAR
Unix and shell programming | Introduction to Unix Operating system | Unix file system | Unix File Permissions | Unix Blocks | Feature of Unix Operating System | Kernel and Shell | Types of Shells
7 mobile app usability testing best practices by UserTestingUserTesting
You should test throughout the development process. That way you can catch problems early, when they are easier to fix. The general rule is: Test early, test often. If you’re doing Agile development, you should conduct user testing every week or two, to validate the work you’ve just done and guide what you do next. We’ve heard heartbreaking stories from companies that left mobile testing until the end of development. They found significant problems, but launched anyway because it was too late to make major changes. A good approach is to test at each stage in the development process.
Does the idea of releasing your next app or mobile website make you queasy? Test away your fears! Download our eBooks to explore fast, easy ways to improve mobile websites and apps at every stage of development: http://info.usertesting.com/Mobile-Usability-Testing-Strategy-eBook.html
This presentation several topics of subjects RDBMS and DBMS including Distributed Database Design,Architecture of Distributed database processing system,Data Communication concept,Concurrency control and recovery. All the topics are briefly described according to syllabus of BCA II and BCA III year subjects.
Unix and shell programming | Unix File System | Unix File Permission | BlocksLOKESH KUMAR
Unix and shell programming | Introduction to Unix Operating system | Unix file system | Unix File Permissions | Unix Blocks | Feature of Unix Operating System | Kernel and Shell | Types of Shells
7 mobile app usability testing best practices by UserTestingUserTesting
You should test throughout the development process. That way you can catch problems early, when they are easier to fix. The general rule is: Test early, test often. If you’re doing Agile development, you should conduct user testing every week or two, to validate the work you’ve just done and guide what you do next. We’ve heard heartbreaking stories from companies that left mobile testing until the end of development. They found significant problems, but launched anyway because it was too late to make major changes. A good approach is to test at each stage in the development process.
Does the idea of releasing your next app or mobile website make you queasy? Test away your fears! Download our eBooks to explore fast, easy ways to improve mobile websites and apps at every stage of development: http://info.usertesting.com/Mobile-Usability-Testing-Strategy-eBook.html
This presentation several topics of subjects RDBMS and DBMS including Distributed Database Design,Architecture of Distributed database processing system,Data Communication concept,Concurrency control and recovery. All the topics are briefly described according to syllabus of BCA II and BCA III year subjects.
How to use any static site generator with GitLab Pages. Ivan Nemytchenko
It is possible to delegate all the routine work of static site generation to GitLab Pages. It is possible because of built-in CI service.
March, 19 2016, Kiev, Ruby Meditation
Learning from ZFS to Scale Storage on and under Containersinside-BigData.com
Evan Powell presented this deck at the MSST 2107 Mass Storage Conference.
"What is so new about the container environment that a new class of storage software is emerging to address these use cases? And can container orchestration systems themselves be part of the solution? As is often the case in storage, metadata matters here. We are implementing in the open source OpenEBS.io some approaches that are in some regards inspired by ZFS to enable much more efficient scale out block storage for containers that itself is containerized. The goal is to enable storage to be treated in many regards as just another application while, of course, also providing storage services to stateful applications in the environment."
Watch the video: http://wp.me/p3RLHQ-gPs
Learn more: blog.openebs.io
and
http://storageconference.us
Sign up for our insideHPC Newsletter: http://insidehpc.com/newsletter
This document describes how XenServer provides and keeps track of the storage supplied to its guests. The first section
is a reminder of how Linux looks at storage and the second section builds on that to explain XenServer storage. Basic
knowledge of Linux is required, as some standard tools are used.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Neuro-symbolic is not enough, we need neuro-*semantic*Frank van Harmelen
Neuro-symbolic (NeSy) AI is on the rise. However, simply machine learning on just any symbolic structure is not sufficient to really harvest the gains of NeSy. These will only be gained when the symbolic structures have an actual semantics. I give an operational definition of semantics as “predictable inference”.
All of this illustrated with link prediction over knowledge graphs, but the argument is general.
Slack (or Teams) Automation for Bonterra Impact Management (fka Social Soluti...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on the notifications, alerts, and approval requests using Slack for Bonterra Impact Management. The solutions covered in this webinar can also be deployed for Microsoft Teams.
Interested in deploying notification automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
7. Use Case
Small number of files (30~100 per VM)
Files either very small (~a few KBs), or very
large (many GBs)
SAN storage is the underlying substrate.
All storage exported by these storage systems
is shared among all ESX servers
8. Design Goals
Metadata overhead should be very low
VM IO throughput and latency should be as
good as directly attached raw device
A clustered lock manager for moderating
access to files among ESX servers
Help VM deterministically react to transient
and non-transient SAN events and error
conditions.
10. VMFS Architecture
A volume is an aggregation of resources and on-disk
locks.
A resource is either an inode, a file block, a sub-
block or an indirect block.
Each lock moderates access to a subset of resources.
Hosts negotiate access to resource by acquiring
relevant locks.
VMFS = a clustered lock manager + a resource
manager + a journaling module + a data mover + a
VM IO manager + POSIX system call frantend
11. VMKernel Logical Volume
VMFS are by default created inside VMKernel
logical volumes. VMKernel logical volumes can
be spanned across multiple devices.
13. Four Resources
file blocks
sub-blocks
pointer blocks
file descriptors
Resources are grouped together into collections called
CLUSTERs and clusters are further grouped together
into CLUSTER GROUPS.
14. Block Mapping
Packed inside inode
Sub block addressing
File block addressing
Pointer block addressing
Can upgrade automatically.
15. System Files
System files are created at file system format
time, and each manages one type of
resources.
16. System Files
Use file blocks.
Same read/write method as regular files.
Checking file data consistency essentially
provides metadata consistency.
17. Cluster Groups
Cluster groups are repeated to create a file system.
An existing VMFS volume grows over unused space
on the disk or spans new disks by laying out new
cluster groups that refer to the newly added space.
VMFS resource manager makes hosts operate on
different and distant cluster groups within a system
file. This reduces the possibility of mutiple hosts
contending on the same lock(s) and increases the
efficiency of the clustered lock manager.
18. On-disk Lock
A single sector data
structure.
Locking is based on lease.
Atomic disk operations (SCSI
reserve-read-modify-write-
SCSI release)
19. On-disk Lock Data Structure
HostID: This is a 128-bit unique identifier that identifies the ESX host that
owns the lock at a given point in time. All zeros means no owner.
Mode: A set of non-zero values to indicate whether a lock is free, held
exclusively, held by multiple hosts for shared read access, or held by
multiple hosts for shared read and write access.
Generation: A monotonically increasing counter, updates every time a lock
is acquired, released or broken. While the hostID field sufficiently
disambiguates operations on a lock from different hosts, this field
disambiguates multiple operations on a lock by the same host.
HBregion: For each valid hostID (if any) currently using the lock, a pointer
to the on disk heartbeat region of the host.
HBgen: A generation number to validate the HBregion reference as being
current or stale. It disambiguates locks held by a given host before and
after a host crash and before and after a storage outage.
20. On-disk Heartbeat
A single sector data structure
Every host accessing a VMSF volume acquires
a heartbeat on disk to declare liveness to
other hosts.
Allocated from a 1MB reserved region of the
volume. 2048 concurrent hosts access.
21. HB Failure Handling
Hosts are free to break locks if heartbeat’s
timestamp does not change for 20 second. Should
replay journal when taking stale lock.
If failing to update heartbeat timestamp in five HB
period (about 15 sec and 40 HB IO tries), host will
fence itself and abort all inflight IOs.
Lock manager tries to rejoin the cluster if IO error is
not permanent, and reclaims HB slot.
22. On-disk Lock & HB
Each host can join a cluster by acquiring a on-
disk HB.
It can also hold thousands of on-disk locks
25. Optimistic Locking
All hosts in a VMFS cluster generally operate on
mutually exclusive subsets of locks on the volume.
A host that is interested in acquiring a given lock will
typically find it to be free on disk.
In stead of acquiring all locks, host first reads all
locks, if they are free, modify in memory metadata
and then upgrade locks and commit.
27. Transaction State Machine w/ op lock
Upgrade Lock
1: reserve disk;
2: issue asynchronous (async) reads of all
required locks;
3: if any lock is acquired by remote host,
abort and fall back to normal TSM;
4: issue async writes of all required locks;
5: wait for all async writes to complete;
6: release disk;
34. Directive SCSI CMD
atomic_test_and_set(block_number, old_image,
new_image)
For VMFS lock manager, new lock algorithm: reads a
lock image from disk, and if the lock is free, issues
an atomic_test_and_set with a new_image
containing host specific hostID, generation and
heartbeat information.
4 IOs -> 2 IOs