The flashcards below were created by user
on FreezingBlue Flashcards.
What is virtualization?
-the creation of substitutes for real resources – abstraction of real resources
Example of virtualization
-Ex. SAN, VLAN, RAID
Advantages of virtualization:
- -Portable virtual machines
- -Consolidation of resources
- -Isolation of virtual machines
Disadvantages of virtualization:
-applications run faster
-the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network.
Storage virtualization (e.g. SAN)
-is the pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console.
- -A virtual machine is a tightly isolated software container that can run its own operating systems and applications as if it were a physical computer.
- -On a given h/w platform (host) – simulated (virtual) machine environments are created
Benefits of system virtualization:
- -consolidation to reduce hw costs
- -workloads consolidation
- -single consolidated view/management
- -portability of virtual machines
- -can be used for testing/training
What is virtual infrastructure?
-Is sharing of physical resources (servers, storage, network) as a dynamic resource pool
- -Type 2 hypervisor
- -host O/S runs virtualization software, unmodified guest O/Ss run isolated from each other (separate virtual machines)
- -Additional resources are required for host O/S
- -(type 1 hypervisor)
- - there’s no host O/S. Virtual machines run on top of type 1 hypervisor directly on a hardware platform
- -No resources are wasted for a Host O/S
- -Higher virtualization efficiency can be achieved
- -Guest O/S is modified to include a call to hypervisor to access h/w resources
- -Guest O/S is “aware” of running in a virtualized environment
- -Makes the structure of hypervisor simpler
- -May make virtual machine more efficient
Disadvantage of paravirtualization
-Guest OS is modified
Full (transparent) virtualization
-Refers to the process of allowing each guest operating systems run unmodified in isolation
Main challenges of transparent virtualization
-Guest OS privileged instructions expect to run in Ring 0
-Modifying a CPU to include extended set of instructions
Hardware-assisted virtualization technology affect virtualization software, such as Vmware by
-It complements it for more efficiency
Virtual Embedded Bridge (VEB)
-a software switch as part of the hypervisor
External Hardware Switch
-switching function performed by an external switch
What is Cloud Computing
-Dynamically scalable, device-independent and task-centric computing resources are provided online, with all charges being on a usage basis.
Some of Cloud Computing defining characteristics?
- -Apps (s/w), processing power and storage (h/w) accessed on the Internet, online
- -Task-centric computing
- -Device/platform independent computing
- -Dynamically scalable, on-demand computing
- -Resources are available with variable, per-usage costs (not fixed)
Advantage of cloud computing over traditional data center
- -Pay-per-use resources
- -Accessible from most devices
- -Promotes collaboration
Disadvantages of cloud computing
Example of cloud computing
- -A User creating a Facebook application
- -A user accessing a Yahoo email account
- -A user accessing a supplier's virtual server to test an application
- -Not an example
- --A user accessing his email account on their company's email server
The fact that cloud computing has no fixed costs makes it more attractive to small companies
- -Software as a Service (Saas)
- -Running existing online applications.
- -Online productivity tools, including word processing, spreadsheet, presentation: GoogleDocs, Zoho, Microsoft)
- -creative web tools - Pixlr, Jaycut, Aviary
- -dedicated business applications: Salesforce, Employease, NetSuite .
- -Available for free or as a subscription service, accessible from any Internet client, facilitate collaboration.
- -The disadvantage is that they are not customized enough, too generic.
A user accessing a cloud supplier's payroll application
-Example of SaaS
- -Platform as a Service (Paas)
- -Environment and a set of tools to create online applications,
- -Allows quick development of applications without much additional cost.
- -Can deploy applications privately or publicly.
- -Limits developers to an existing set of tools and languages and platform dependency.
Using a browser, you develop and run your ecommerce website and application on a supplier's server that runs Java-based programming tools
-Example of PaaS
- -Infrastructure as a Service (Iaas), sometimes known as Hardware as a Service (Haas).
- -Allows a business to run their own applications on the cloud hw without investing in its own hw infrastructure.
- -Cloud suppliers can use actual physical or virtual servers to host applications.
What are 4 types of IaaS?
-private, dedicated, hybrid and cloud hosting
-(certain physical servers are dedicated to one customer)
-(customer rents physical servers on demand as needed)
-(a mix of physical and virtual servers to reduce cost and increase flexibility)
-(customer rents virtual servers on demand as needed, sometimes hourly).
What are some of concerns and issues with Cloud Computing today?
- -Data theft/loss
What is caching?
- -Temporary storage of frequently accessed data (duplicating original data stored somewhere else)
- -Reduces access time/latency for clients
- -Reduces bandwidth usage
- -Reduces load on a server
-for a single user
(Proxy) Shared cache (forward and reverse)
-same principle for multiple users
Forward Proxy Caching
- -Cache located closer to the client
- -Usually deployed by an ISP
- -Decreases bandwidth usage (ISP to the Internet link in the example below)
Reverse Proxy Caching
- -Aka gateway proxy or web accelerators
- -Cache proxy located closer to the origin web server
- -Usually deployed by an Web hosting ISP
- -Decreases load on the web server
- -Several reverse proxy caches implemented together can form a Content Delivery Network
-how long the document stays “fresh” or can be used from cache without rechecking the origin server
-[seconds] — specifies the maximum amount of time that an representation will be considered fresh.
-tells all caches how long the associated representation is fresh for
- – compare the cached document to the origin document once it’s not “fresh” anymore
- -Are used by caches to compare the cached document to the original document for changes
- -If validator is not present and no freshness information is available, the document won’t be cached
-the last time that the document last changed
-unique identifiers that generated by the server and changed every time the representation does
- – done by switches/routers, clients are unaware
- -To avoid configuring each client to point to cache proxy
- -Can be accomplished using inline cache, layer 4 switch, WCCP, policy-based routing
- -Cache pretend to be the origin server, tricks client into thinking it's connected to the server
Content Delivery Networks
- -Network of computers that deliver content on the web.
- -Content pushed-out/delivered “closer” to the clients
- -Designed to improve Internet performance (i.e. decrease latency for clients, decrease bandwidth use)
- -Consists of origin server, surrogate (edge servers)
- -Caching and server load balancing techniques are used
- -ESI (Edge-Side Includes) – open standard markup language to augment HTML for help with dynamic delivery and assembly of Web documents
Benefits of Content Delivery Networks
- Designed to improve Internet performance
- (i.e. decrease latency for clients, decrease bandwidth use)
CDN edge server placement: enter deep vs bring home
- enter deep: push CDN servers deep into many access networks
- -close to users -used by Akamai, 1700 locations
- bring home: smaller number (10's) of larger clusters in POPs near (but not within) access networks)
- -used by Limelight
CDN cluster selection strategies
- challenge: how does CDN DNS select “good” CDN node to stream to client
- -pick CDN node geographically closest to client
- -pick CDN node with shortest delay (or min # hops) to client (CDN nodes periodically ping access ISPs, reporting results to CDN DNS)
- -IP anycast
- alternative: let client decide - give client a list of several CDN servers
- -client pings servers, picks “best”
- -Netflix approach
Netflix case study
- 30% downstream US traffic in 2011
- owns very little infrastructure, uses 3rd party services:
- -own registration, payment servers
- -Amazon (3rd party) cloud services:
- --Netflix uploads studio master to Amazon cloud
- --create multiple version of movie (different endodings) in cloud
- --upload versions from cloud to CDNs
- --Cloud hosts Netflix web pages for user browsing
- -three 3rd party CDNs host/stream Netflix content: Akamai, Limelight, Level-3
Comcast is a global media and technology company committed to bringing the best in media and technology to its customers. Demand for the company’s new X1 delivery platform exceeded the capacity of its on-premise data centers. By turning to AWS, Comcast is able to quickly add capacity with Amazon VPC and Direct Connect, expanding their data centers as they scale to provide interactive entertainment on demand.
The US Food and Drug Administration (FDA) protects and promotes public health. The agency, which receives 100,000 handwritten reports of adverse drug affects each year, needed a way to make the data entry process more efficient and reduce costs. By using AWS, the FDA and AWS Partner Captricity quickly turn manual reports into machine-readable information with 99.7% accuracy, reducing costs from $29 per page to $0.25 per page.
Dole Food Company is an American-based agricultural multinational corporation that distributes its products in 90 countries. Searching for a solution to host its MSFT SharePoint sites, the company chose AWS because of cost, efficiency, and to improve operational efficiency. By running on AWS, Dole can launch a new SharePoint website in minutes, host business intelligence and mobile applications globally, and estimates savings $350,000 in operating expenses.
Adobe Systems Managed Services program delivers enterprise software such as Adobe LiveCycle Forms , Adobe Connect conferencing software, and Adobe CQ5 to Fortune 100 companies, large multi-national corporations, and government agencies. Adobe uses AWS to provide multi-terabyte operating environments for its customers. By integrating its systems with the AWS Cloud, Adobe can focus on deploying and operating its own software instead of infrastructure.