☁Cloud-Computing

Object Stores Characteristics of Cloud Systems Object storage design principles 🟨++ We don’t want the hierarchy that is common in Filesystems, so we need to simplify that and have these four principles: Black-box objects Flat and global key-value model (trivial model, easy to access, without the need to trasverse a file hierarchy). Flexible metadata Commodity hardware (the battery idea of Tesla until 2017). Object storage usages 🟩 Object storage are useful to store things that are usually read-intensive. Some examples are ...

CDNs are intermediary servers that replicate read intensive data to provide better performance when user requests them. A close relative of CDNs is edge computing (e.g. gaming stations) where lots of computation is done directly close to the user. Types of CDNs Mainly three types of CDNs: Highly distributed ones. Database based ones. Ad-hoc CDNs. Advantages and disadvantages The main reason we use CDNs is to lower the value of latency: we are in fact bringing the data closer to the user. We have much less data in length to be transmitted. Yet we have some disadvantages too: ...

Reliability is the ability of a system to remain operational over time, i.e., to offer the service it was designed for. Cloud Hardware and software fails. In this note, we will try to find methods to analyze and predict when components fail, and how we can prevent this problem. Defining the vocabulary Availability $$ \text{Availability} = \frac{\text{Uptime}}{\text{Uptime} + \text{Downtime}} $$MTTF: Mean Time To Failure $$ \text{MTTF} = \frac{1}{r} $$ This definition does not include repair time, and assumes the failures are independent with each other. ...

Devices Categorizzazione (6)🟨- Trasferimento dei dati Accesso al device sinfonia del trasferimento condivisone fra processi Velocità del trasferimento I/O direction (scrittura o lettura) Vediamo che molte caratteristiche sono riguardo il trasferimento Slide categorizzazione I/O Blocchi o caratteri 🟩- Slide devices blocchi o caratteri Tecniche di gestione devices (4) 🟨- Buffering Possiamo mettere un buffer per favorire la comunicazione fra i devices. la cosa migliore che fa è creare maggiore efficienza. Un altro motivo è la velocità diversa di consumo. ...

Queueing theory is the theory behind what happens when you have lots of jobs, scarce resources, and subsequently long queues and delays. It is literally the “theory of queues”: what makes queues appear and how to make them go away. This is basically what happens in clusters, where you have a limited number of workers that need to execute a number of jobs. We need some little maths to model the stochastic process of request arrivals. ...

Cloud Computing: An Overview Cloud shifted the paradigm from owning hardware to renting computing resources on-demand. Hardware became a service. Key Players in the Cloud Industry 🟨 The cloud computing market is dominated by several major providers, often referred to as the “Big Seven”, also called hyper-scalers. They are usually not interested in making it interoperable (they prefer the lock-in). Amazon Web Services (AWS): The largest provider, offering a comprehensive suite of cloud services. Microsoft Azure: Known for deep integration with enterprise systems and hybrid cloud solutions. Google Cloud Platform (GCP): Excels in data analytics, AI/ML, and Kubernetes-based solutions. IBM Cloud: Focuses on hybrid cloud and enterprise-grade AI. Oracle Cloud: Specializes in database solutions and enterprise applications. Alibaba Cloud: The leading provider in Asia, offering services similar to AWS. Salesforce: A major player in SaaS, particularly for CRM and business applications. These providers collectively control the majority of the global cloud infrastructure market, enabling scalable and on-demand computing resources for businesses worldwide. Capital and Operational Expenses in the Cloud Definition for CapEx and OpEx 🟥 Cloud computing transforms traditional IT cost structures by shifting expenses from capital expenditures (CapEx), such as purchasing servers and data centers, to operational expenditures (OpEx), where users pay only for the resources they consume. ...

We need to find an efficient and effective manner to allocate the resources around. This is what the resource management layer does. Introduction to the problem What is Cluster Resource Management? Most of the time, the user specifies an amount of resources, and then the cluster decides how much to allocate (but approaches like (Delimitrou & Kozyrakis 2014), do it differently). There are mainly two parts in cluster resource management: Allocation: deciding how many resources an application. Assignment: from which physical machine you can effectively put the application. Types of management architectures We mainly divide the management architectures in three ways: ...

Containers What is a Container 🟨++ We have explored virtual machines in Architettura software del OS#Macchine virtuali. Containers do not virtualize everything, but just the environment where the application is run. This includes: Libraries Binaries We can see it as a lightweight VM, even if they do not offer the full level of isolation of traditional virtual machines. Image from the course slides Containers vs. Virtual Machines (VMs) 🟨– Docker is one of the most famous containerization tools, but there are many others like Podman, LXC, or Singularity. They have different roles and scopes. ...

A seconda dell’utilizzatore l’OS può essere molte cose, come solamente l’interfaccia se sei un programmatore, servizi (se sei un utente, ma gran parte dei servizi sono astratti e l’utente ne può anche essere a non-conoscenza). Ma se sei un programmatore OS ti interessa capire le componenti principali dell’OS Slide componenti OS alto livello Introduzione sui componenti (salto) Questa parte la salto perché è una descrizione molto generale di cosa si occupa L’os verso drivers, processi, filesystem I/O, quindi non è molto importante ...

Introduction to cluster management How can we allocate the resources in a cluster in an efficient manner? How can we allocate resources fairly? Two step allocations 🟨++ There are two main kinds of allocation: first you need to allocate resources to a process, then allocate the process physically in the cluster. Private and public cluster management 🟥++ Cluster management could be private or public. Private means every app is managing their own sub-cluster: each app receives a private, static set of resources. Here it is easier to manage hardware for various needs. Public means there is a big cluster, like standard third party ...