Lecture3_Enabling.pdf

CS 5610 Introduction to Cloud Computing 1  Lecture 3 Cloud Computing Enabling Technology [email protected] 2  Learning Objectives  Understand the following cloud-enabling technology:...

CS 5610 Introduction to Cloud Computing 1  Lecture 3 Cloud Computing Enabling Technology [email protected] 2  Learning Objectives  Understand the following cloud-enabling technology: Internet and Web Technology Modern Virtualization Technology Multitenant Technology Cloud Data Center Technology 3  Cloud-Enabling Technology  Modern-day clouds are underpinned by a set of primary technology components that collectively enable key features and characteristics associated with contemporary cloud computing: 1. Internet and Web Technology 2. Virtualization Technology 3. Multitenant Technology 4. Cloud Data Center Technology 4  Cloud-Enabling Technology 1: Internet and Web Technology  Recall the definition and major characteristics of Cloud Computing  Internet and Web Technology plays important role in cloud computing: Enabling communication Supporting service implementation and delivery 5  Internet  All clouds must be connected to a network.  The Internet (or internetworks) enables the remote provisioning of IT resources and directly supports ubiquitous network access.  The Internet is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a network of networks that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies. 6  Internet Organizations  Internet is a decentralized network of networks, meaning there is no single organization that controls the entire internet. Instead, the Internet operates based on a collaborative and distributed model, involving multiple organizations. Internet Corporation for Assigned Names and Numbers (ICANN) o Manages the global Domain Name System (DNS) Internet Assigned Numbers Authority (IANA) o Manages global IP address allocation Internet Engineering Task Force (IETF) https://en.wikipedia.org/wiki/ o Develops and promotes internet standards List_of_Internet_organizations World Wide Web Consortium (W3C) o Develops standards for the World Wide Web 7  Internet Service Providers  An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can deploy, operate, and manage their networks in addition to selecting partner ISPs for interconnection.  Types of ISPs Dial-Up ISPs o Early internet access, Modem-based Broadband ISPs o DSL, Cable, Fiber optics Wireless ISPs o Satellite, Cellular (3G, 4G, 5G) Local ISPs, Backbone ISPs 8 Internet Service Providers Figure – Cloud consumers and cloud providers are connected thru local ISPs and backbone ISPs 9  Selection of ISPs  Reliable connectivity must be provided by the ISPs for both cloud provider and cloud consumer.  Cloud-based IT solutions need to be assessed against business requirements that are affected by Internet QoS: Availability Bandwidth o is critical for applications that require substantial amounts of data to be transferred to and from the cloud Latency o is critical for applications with a business requirement of swift response times. 10  Selection of ISPs  The service levels of Internet connections between cloud consumers and cloud providers are determined by their ISPs, which are usually different and therefore include multiple ISP networks in their paths.  QoS management across multiple ISPs requires the collaboration of the ISPs on both sides to ensure that their end-to-end service levels are sufficient for business requirements. 11  Packet Switching and Router Based Interconnectivity  The Internet relies on some key technologies to function effectively.  Two fundamental technologies are packet switching and router-based interconnectivity. 12  Packet Switching  In Packet switching, stream of data is broken into smaller blocks of data (packets). Each of these packets are then sent independently over the network.  Packet switching allows for more efficient utilization of bandwidth resources compared with circuit switching. 13  Router-based Interconnectivity  A router is a device that is connected to multiple networks through which it forwards packets.  Routers process and forward packet individually while maintaining the network topology information and determining the best path to the destination. Routing protocols: BGP, IS-IS, RIP, OSPF, etc. 14 Router-based Interconnectivity 15 OSI Model and TCP/IP Model 16  Physical Networks  Physical Networks IP packets are transmitted through underlying physical networks that connect adjacent nodes. Corresponds to the Network Interface Layer in TCP/IP model. Corresponds to Physical layer + Data Link layer In OSI model. There are many wired or wireless physical technologies/mediums, such as, Ethernet, SONET/OTN, Wi-Fi, 4G/5G networks, satellite, Bluetooth, etc. 17  Challenge/Discussion  Get the full names of BAN/PAN/LAN/CAN/MAN/WAN for networks. 18  Network Layer  IP (Internet Protocol) IP versions: IPv4, IPv6 o IP version 4 (IPv4) has been around for more than 40 years; 32 bits o IP version 6 (IPv6) is being used to phase out IPv4; 128 bits Types of IP addresses o IPv4: private, public, multicast, broadcast, link-local, loopback o IPv6: link-local, unique local, global unicast, multicast, anycast o Https://en.wikipedia.org/wiki/IP_address 19  IPv4 vs IPv6 “No IoT without IPv6” https://www.computerworld.com/article/3071625/internet-of-things/no-iot-without- ipv6.html 20  Transport Layer  Transport Layer Protocol Transport layer protocols provide end-to-end communication for applications Transmission Control Protocol(TCP) and User Datagram Protocol(UDP) o TCP: email, ftp, web browsing o UDP: some multicast and streaming applications, voice and video 21  Application Layer  Application Layer Protocols Protocols such as HTTP, HTTPS, SMTP for email, BitTorrent for P2P, and SIP for IP telephony use transport layer protocols for data packet transferring over the Internet. HTTP: HyperText Transfer Protocol HTTPS: Hypertext Transfer Protocol Secure SMTP: Simple Mail Transfer Protocol SIP: Session Initiation Protocol https://en.wikipedia.org/wiki/Internet_Protocol 22  Challenge/Discussion  List some example applications using TCP and examples using UDP as their transport protocols. 23  Web Technology  Due to web browser universality and the ease of web development, web technology plays a crucial role in both the implementation and management of cloud services.  Implementation Medium Web Applications o Simple websites to complex enterprise solutions APIs and Microservices o Cloud services frequently use RESTful APIs Serverless Computing o The functions are often triggered via HTTP requests 24  Web Technology  Web technology plays a crucial role both the implementation and management of cloud services.  Management Interface Web-Based Dashboards Administrative Portals Monitoring and Logging 25  World Wide Web  The World Wide Web (WWW) is a system of interlinked IT resources that are accessed through the Internet.  The basic components of the Web are Web Browsers Web Servers Web Pages URLs (Uniform Resource Locators)  Other components, such as proxies, caching services, gateways, and load balancers, are used to improve Web application/service characteristics such as scalability and security. 26  Web Technology  Three fundamental elements comprise the technology architecture of the Web. Uniform Resource Locatora(URLs) Hypertext Transfer Protocol(HTTP/HTTPS) Markup Languages(e.g. HTML) Data Representation Formats 27  Web Technology  Uniform Resource Locator(URL): A standard syntax used for creating identifiers that point to Web-based resources, the URL is often structured using a logical network location. colloquially termed a web address (URI contains two subsets, URN, which tell the name, and URL, which tells the location.)  Hypertext Transfer Protocol(HTTP/HTTPS) This is the primary communications protocol used to exchange content and data throughout the World Wide Web. web pages are typically transmitted via HTTP/HTTPS. 28  Web Technology  Markup Language(HTML) Markup languages provide a lightweight means of expressing Web-centric data and metadata. The primary markup languages are HTML and XML. HTML o Hypertext Markup Language (HTML) is the standard markup language for creating web pages and web applications. o With Cascading Style Sheets (CSS) and JavaScript, it forms a triad of cornerstone technologies for the World Wide Web XML o Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. 29  Web Technology  Data File Formats: JSON o JavaScript Object Notation (JSON) is an open-standard file format that uses human-readable text to transmit data objects consisting of attribute–value pairs and array data types. o It is a common data format used for asynchronous browser–server communication, including as a replacement for XML in some AJAX- style systems. YAML o YAML (YAML Ain’t Markup Language) is a human-readable data serialization format used for configuration files and data exchange between languages with different data structures. o It is often compared to JSON and XML due to its role in data representation. 30 Format Comparison 31  Web Application and Web Service  A web application is a software application that runs on a web server and is accessed through a web browser over the Internet or an intranet. Unlike traditional desktop applications, web applications do not require installation on a user’s local device.  A web service is a standardized way for different applications or systems to communicate over the web using XML or JSON. It enables interoperability between different software systems. 32  Web Applications  Web applications are prevalent in various cloud-based environments due to their high accessibility.  Web apps are employed to implement and deliver a wide range of cloud-based services and features.  Web apps can be hosted on the cloud using various cloud resources and products.  Web app development can also be cloud-native, utilizing a variety of cloud tools and services. 33 Web Applications 34  Web Applications  Web App Development Languages: PHP: Popular general-purpose scripting language that is especially suited to web development. NodeJS: Event-driven I/O server-side JavaScript environment. JavaScript: Programming language of HTML and the web. HTML5: Markup language, the latest version of HTML and XHTML. CSS3: Latest version of cascading style sheets used in front-end development of sites and applications. Python: Programming language that lets you work quickly and integrate systems more effectively. Ruby: A dynamic, open source programming language with a focus on simplicity and productivity. Scala: Scala is a pure-bred object-oriented language allowing a gradual, easy migration to a more functional style. SQL: Stands for structured query language used with relational databases. Golang: Open source programming language that makes it easy to build simple, reliable, and efficient software. Rust: Systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety. TypeScript: Open source programming language that is a superset of JavaScript which compiles to plain JavaScript Etc. 35  Web Applications  Web Development Frameworks React, Angular, Vue, Ember, jQuery Ruby, Django, Laravel, ASP.net, Express 36  RESTful  Most web-based services/applications are RESTful. In contrast to SOAP (Simple Object Access Protocol) web services  Representational State Transfer (or REST) services/apps use existing Internet and WWW concepts/technologies REST uses the HTTP methods. Communication with a RESTful service is typically quick and uses existing content standards for packaging its messaging. Common formats are XML or JSON, but plain text, CSV, and RSS can also be used REST is stateless, meaning does not keep a client state on the server. 37  REST Operations  REST typically use the HTTP methods.  Basic Operation Types (GET, DELETE, POST, PUT) in HTTP.  These HTTP methods can provide four different points of access to a RESTful service – CRUD operations 38  Cloud-Enabling Technology 2: Modern Virtualization Technology Definition of virtualization Types of virtualization Resource sharing and replication Hypervisors Containers 39  Virtualization Technology  “Virtualization” is the process of converting a physical IT resource into virtual IT resource(s). represents a technology used for the creation of virtual instances of IT resources.  Most types of IT resources can be virtualized, including: Servers – Physical server(s) can be abstracted into virtual server(s). Storage – Physical storage device(s) can be abstracted into virtual storage device(s). Network – Physical routers and switches can be abstracted into logical/virtual network fabrics, such as VLANs. 40  Benefits of Virtualization Technology  Modern virtualization overcomes performance, reliability and scalability limitations of traditional virtualization platforms  Modern virtualization enables resource sharing and resource replication, offering benefits such as efficient utilization of hardware, cost savings, high availability.  Impact on cloud computing: modern virtualization is the foundation of cloud computing technology 41  Resource Sharing  Virtualization technology enables multiple different virtual IT resources to share one physical IT resource. It is also possible to use multiple IT resources to create one virtual IT resource.  This fundamental capability directly supports common cloud features, such as: on-demand usage, resource pooling, elasticity, scalability, and resiliency. 42  Resource Replication  Virtualization technology also enables easy resource manipulation and replication in cloud environment. Cloning and manipulating virtual IT resources is much easier than duplicating physical hardware. E.g., o Virtual servers are created as virtual disk images that contain binary file copies of hard disk content. o These virtual disk images are accessible to the host’s operating system, meaning simple file operations, such as copy, move and paste, can be used to replicate, migrate, and back up the virtual server. 43  Resource Replication  Ease of replication of virtual instances enables many essential cloud IT tasks: Instantaneous deployment o Standardized virtual machine images (pre-packaged virtual hardware capabilities, guest OS, and application software) Rapid scaling o Agility in the migration and deployment of a virtual machine’s new instances Ability to roll back o Instantaneous creation of VM snapshots by saving the state of the virtual server’s memory and hard disk image to a host-based file Support of business continuity o Efficient backup and restoration procedures, as well as the creation of multiple instances of critical IT resources and applications. 44 Types of Virtualization There are a variety of virtualization technologies used in cloud environments, each serving different purposes and use cases. 45  Hypervisors  A Hypervisor, also known as a Virtual Machine Monitor (VMM), is software or firmware that creates and manages virtual machines (VMs) on a physical server. enables multiple virtual machines (VMs) to run on a single physical server  Type of Hypervisors: Type 1 Hypervisor o also called Bare-Metal, native, or hardware based hypervisor Type 2 Hypervisor: o also called Hosted, or OS based hypervisor 46 Types of Hypervisors 47  Type 1 Hypervisor  A Type 1 hypervisor (bare-metal, native, hardware-based) is a virtualization software installed directly on the physical hardware.  A Type 1 hypervisor exists as a thin layer of software that handles hardware management functions to establish a virtualization management layer. Device drivers and system services are optimized for the provisioning of virtual servers. 48 Type 1 Hypervisor Figure – Type-1 does not require a host operating system. 49  Type 1 Hypervisor  Type 1 Hypervisor is essentially used to optimize performance and reduce overhead inherent to the coordination that enables multiple virtual servers to interact with the same hardware platform.  There might be compatibility issue: Hardware device drivers may not be as available to hypervisor platforms as they are to operating systems. 50  Type 2 Hypervisor  Type 2 Hypervisor (OS-based, hosted) is a virtualization software installed in a pre-existing host operating system. Figure – The Hypervisor( VMM) is installed into a full host operating system and subsequently used to generate virtual machines. 51  Type 2 Hypervisor ✓ For example: A user whose workstation is installed with a specific version of Windows wants to generate virtual servers and installs virtualization software (e.g., VirtualBox) into the host operating system like any other program. The host operating system can provide hardware devices with the necessary support, operating system virtualization can rectify hardware compatibility issues. 52  Type 2 Hypervisor  Type 2 Hypervisor can introduce demands and issues related to performance overhead : The host operating system consumes CPU, memory, and other hardware IT resources. Hardware-related calls from guest operating systems need to traverse several layers to and from the hardware, which decreases overall performance. 53  Comparison of Hypervisor Types Feature Type 1 Hypervisor Type 2 Hypervisor Installation Directly on hardware On top of a host OS Lower, due to OS layer Performance High, minimal overhead overhead Strong, direct hardware Lower, depends on host Security access OS security Limited, specific drivers Broad, uses host OS Driver Compatibility required drivers Easier, user-friendly Management Complexity Advanced, more complex interfaces Often higher (licensed Cost Generally lower or free products) High, enterprise-level Limited, best for small- Scalability solutions scale environments 54  Cloud Hypervisors  Cloud providers most commonly deploy a Type 1 (bare-metal, native) hypervisor, where virtualization software is installed directly on the hardware. They generally perform better and more efficiently than hosted hypervisors. As well, because bare-metal hypervisors are isolated from the attack-prone operating system, they are more secure. 55  Containers  A container is a lightweight, portable unit that includes an application and all of its dependencies, libraries, and configuration files needed for the application to run consistently across different computing environments.  Container (containerization) technology is a form of virtualization at the operating system level that allows applications to be packaged with their dependencies and run in isolated environments called containers.  The major public cloud computing providers, including AWS, Azure and Google Cloud have embraced container technology. 56  Containers vs. VMs Containers are more efficient/light-weighted than VMs Containers have better portability than VMs 57  Container Figure - A virtualized application running in a container can be deployed anywhere its corresponding containerization engine is installed, regardless of underlying hardware or operating system architectures. 58  Container Software  Adoption of containers grows by 20%~30% annually.  Docker, Kubernets, LXC, etc. 59  Challenge/Discussion  Search and list 2+ Type-1 hypervisor products; 2+ Type-2 hypervisors.  Is Microsoft Hyper-V type 1 or 2? 60  Cloud-Enabling Technology 3: Multitenant Technology  Multitenant (multitenancy) technology is a design principle in software architecture where a single instance of a software application serves multiple clients or organizations, known as tenants.  Through multitenancy, IT resources can be dynamically assigned and reassigned, according to cloud service consumer demands.  Cloud computing commonly adopts the multitenancy technology and runs its applications for multiple cloud customers to access. 61 Multitenant Technology 62  Cloud Multitenancy  Cloud multitenancy enables one application to serve different cloud consumers (tenants) whereby each is isolated from the others Consumers do not have access to data and configuration information that is not their own This type of application is typical with SaaS implementations. o Microsoft 365, Dropbox, Zendesk, Salesforce, Google Workspace 63  Cloud Multitenancy  Features of Multitenancy in SaaS: Single Application Instance: One version of the software runs on the provider’s infrastructure. Data Isolation: Each tenant’s data is kept separate, usually through logical separation. Shared Resources: Infrastructure resources such as servers, storage, and networks are shared among tenants. Tenant-Specific Customization: Tenants can customize certain aspects of the application (e.g., interface themes, user roles), but core functionality remains the same. 64 Cloud Multitenancy Figure - A multitenant application that is serving multiple cloud service consumers simultaneously. This type of application is typical with SaaS implementations. 65  Challenge/Discussion  What is the difference(s) between virtualization technology and multitenancy technology? 66 Cloud-Enabling Technology 4: Cloud Data Center Technology 67  Cloud Data Center Technology  Modern data centers exist as specialized infrastructure used to house centralized IT resources, such as servers, databases, networking devices, and software systems.  Why data center? Grouping IT resources in close proximity with one another, rather than having them geographically dispersed, allows for power sharing/saving, higher efficiency in shared IT resource usage, and improved accessibility for IT personnel. Data centers are usually located in areas where power and land are cheaper. 68  Data Center Technology  Data centers are typically comprised of the following technologies and components: Virtualization Standardization and Modularity Automation Remote operation and management High availability Security-aware design, operation, and management Hardware (Computing, Storage, Network) Components Supporting Facilities 69  Data Center Technology: Virtualization  Data centers consist of both physical and virtualized IT resources.  The physical IT resource layer refers to the facility infrastructure that houses computing/networking/storage systems and equipment and their operating systems.  Various virtualization technologies are used to provide virtualized instances of IT resources.  The virtualized components are easier to allocate, release, operate, monitor, and control. 70  Data Center Technology: Standardization and Modularity  Data centers are built upon standardized commodity hardware and designed with modular architectures, aggregating multiple identical building blocks of facility infrastructure and equipment to support scalability, growth, and speedy hardware replacements.  “Standardization and Modularity” are key to reducing investment and operational costs as they enable economies of scale for the procurement, acquisition, deployment, operation, and maintenance processes. 71  Data Center Technology: Automation  Data centers have specialized platforms that automate tasks like provisioning, configuration, patching, and monitoring without supervision.  Advances in data center management platforms and tools enable self-configuration and self-recover. 72  Data Center Technology: Remote Operation and Management  Most of the operational and administrative tasks of IT resources in data centers are commanded through the network’s remote consoles and management systems.  Technical personnel are not required to visit the dedicated rooms except equipment handling, cabling, hardware level installation. 73  Data Center Technology: High Availability  Outages significantly impact business continuity for the organizations  Data centers are designed to operate with higher levels of redundancy to sustain availability.  Redundancy, failover, backup, disaster recovery mechanisms are implemented in cloud data centers.  Data centers usually have redundant, uninterruptable power supplies, cabling, and environmental control subsystems in anticipation of system failure, along with communication links and clustered hardware for load balancing. 74  Data Center Technology: Security-aware Design, Operation, and Management  The number of security attacks continues to grow year by year.  The cost of a breach of security can have some devastating consequences both on the companies and on the customers whose data was breached.  Requirements for security, such as physical, logical access controls and data recovery strategies, need to be thorough and comprehensive for data centers.  The security technologies and tools commonly used in Data Centers include packet-filtering technologies such as ACLs, firewalls, Intrusion detection systems (IDS) and intrusion prevention systems (IPS), etc. 75  Data Center Technology: Computing Hardware  Computing in data centers is often executed by standardized commodity servers that have substantial computing power.  Several computing hardware technologies are integrated into these modular servers: - Rackmount form factor server design - A power-efficient multi-core CPU architecture that houses hundred of processing cores in a single unit of standardized racks. - Support for different hardware processing architectures, such as x86-32bits, x86-64, RISC, ARM. - Redundant and hot-swappable 76  Data Center Technology: Storage Hardware  Data centers have specialized storage systems that maintain enormous amounts of digital information.  Storage systems usually involve the following technologies: Disk Arrays I/O Caching Hot-Swappable Disks Fast Data Replication Mechanisms 77  Data Center Technology: Storage Hardware Disk Array o These arrays inherently divide and replicate data among multiple physical drives, and increase performance and redundancy by including disks. This technology is often implemented using RAID. I/O Caching o This is generally performed through hard disk array controllers, which enhance disk access times and performance by data caching. Hot-Swappable Disks o These can be safely removed from arrays without requiring prior powering down. Fast Data Replication Mechanisms o Data Replication is the process of storing data in more than one site or node. It is useful in improving the availability of data. 78  Data Center Technology: Storage Hardware RAID - Redundant Arrays of Independent Disks HDD (Hard Disk Drive) SSD (Solid State Drive) RAID 0 is primarily used in applications that require high performance and are able to tolerate lower reliability; https://en.wikipedia.org/wiki/St RAID 1 does not increase performance; RAID 1 is an andard_RAID_levels excellent option when data protection and redundancy is your primary goal. 79  Data Center Technology: Storage Hardware  Storage devices can be networked and shared. The networked storage devices usually fall into one of the following 2 categories: Storage Area Network (SAN) o Physical data storage media are connected through a dedicated network switch(e.g., Fiber Channel) and provide block-level data storage access using industry-standard protocols, such as the Small Computer System Interface(SCSI). Network-Attached Storage (NAS) o Network-attached storage (NAS) is dedicated file storage that enables multiple users and client devices to retrieve data from centralized disk capacity. 80 Data Center Technology: SAN vs NAS 81  Data Center Technology: Networking Hardware  Data centers require extensive network hardware in order to enable multiple levels of connectivity.  The data center networking infrastructure is usually broken down into 3 networking subsystems. 1. Carrier and External Networks Interconnection (WAN) 2. LANs 3. Storage networking subsystems( such as SAN Switches, NAS Gateway, etc.) 82  Data Center Technology: Networking Hardware Carrier and External Networks Interconnection (WAN) ▪ A subsystem related to the internetworking infrastructure and comprised of routers/gateways that provide routing and connection to the external WAN. LAN ▪ The LAN constitutes the internal LAN and provides high- performance and redundant connectivity for the data center’s IT resources. (usually using Giga/10G/100G Ethernet) Storage networking ▪ Related to the implementation of SANs and NAS devices that provide connectivity between servers and storage systems. 83  Data Center Technology: Supporting Facilities  Data center facilities are custom-designed locations that are outfitted with specialized computing, storage, and network equipment.  These facilities have several functional layout areas.  The supporting facility functionalities include: various power supplies, cabling, and environmental control stations that regulate heating, cooling, ventilation, air-conditioning, fire protection, and other related subsystems. 84  Data Center Tour  https://news.microsoft.com/stories/microsoft-datacenter-tour/  https://www.youtube.com/watch?v=q6WlzHLxNKI 85  Summary of Key Points In this lecture, we learned the major cloud enabling technologies: Internet and Web Technology Modern Virtualization Technology Multitenant Technology Cloud Data Center Technology 87  Summary of Internet/Web Technology  Cloud consumers and cloud providers typically use the Internet to communicate.  The main components of internetworking architecture are packet switching and router based interconnectivity.  Internet organizations include ICANN, IANA, IETF, W3C, etc.  Internet protocols: HTTP, TCP, UDP, IP, routing  There are various BAN/PAN/LAN/CAN/MAN/WAN networks. 88  Summary of Internet/Web Technology  Web technology is very commonly used for cloud service implementation and for front-ends user to remotely manage cloud-based IT resources.  Fundamental technologies of web architecture include URL, HTTP, HTML, XML, JSON, etc.  Web Applications typically have client, server, and database  There are many languages and frameworks for web app development  Most web based applications/services are RESTful. 89  Summary of Virtualization Technology  Many types of IT resources can be virtualized including servers, storage, and networks.  Two types of Hypervisors, Type 1 (bare metal) and Type 2 (hosted).  Cloud providers most commonly deploy a Type 1 (bare-metal, native) hypervisor, where virtualization software is installed directly on the hardware.  A container is a lightweight, portable unit that includes an application and all of its dependencies. 90  Summary of Multitenant Technology  Multitenant technology ensures multiple tenants access the same application simultaneously while remaining unaware of each other.  Multitenant applications are typical with SaaS implementations in cloud environment. 91  Summary of Data Center Technology  A data center is a specialized IT infrastructure that houses centralized IT resources, such as servers, databases and software systems.  Data center IT hardware is typically comprised of standardized commodity computing hardware, storage hardware, and network hardware.  Other technologies used in data center: virtualization, automation, remote operation, high availability, security aware design, supporting facilities. 92