in the first episode we'll be talking about what cloud computing is but also what is the most important vocabulary

that you should understand when working with cloud in general it both describes what cloud computing is but also what

are its benefits stay tuned let's look at the objectives of the first episode today we'll learn what

cloud computing is but also what are its benefits by learning the most important vocabulary like high availability

scalability elasticity agility fault tolerance and also disaster recovery let's start with cloud computing while

computing is a delivery model for services services like storage services as whenever you're storing your

unstructured or structured data in files and databases while delivers you thousands of services to do so you

pretty much can choose any technology that is popular in the market and you will be able to use it with an ear

harsher environment in this case storage doesn't only mean storing data but also all the services and tools that allow

you to migrate your data to the cloud once your data is in the cloud you will need a computer resources like a Windows

virtual machines maybe a Linux ones web containers or any of the hundreds of services available in the cloud because

cloud is about creating applications whenever those our web AI machine learning reporting any kind of

applications out there additionally once you have your components you need to be able to somehow connect them to each

other securely the cloud delivers you with said functionalities to create secure networking between those

components but also your company and because your entire platform is managed in the cloud cloud also needs to deliver

you of analytic capabilities so you can review your performance and telemetry data for your services you can perform

operations the list of the services delivered by cloud computing is much longer than this but those are the four

main ones and four that are tested by the exam all of those services of course are

delivered over the internet and this is basically what cloud is delivering services like this doesn't make a cloud

computing yet now competing needs will also fulfill and characteristics first characteristic

that we will learn today is scalability imagine you have a resource that resource can be anything it can be a web

application it can be a database in can be a virtual machine that gives you a way to scale up this virtual machine by

increasing its size increasing size of the resource basically means adding more power like CPU memory or maybe faster

storage in this case we are moving along the vertical line that's why this is called vertical scaling and increasing

the size of the resource is called scaling up if you decrease the size decrease the power of the machine this

is called scaling it down besides changing the size of your research changing the power of that resource you

can also scale by adding more resources to your environment so increasing the amount of the resources themselves in

this case we are moving along the horizontal line that's why this is called horizontal scaling if you

increase the amount of your resources this is called scaling out if you decrease the amount of resources this is

called scaling in so to summarize scalability is an ability of the system to scale in this case scaling is a

process of adding or removing resources remember that in this case resources might both mean d virtual resources like

CPU memory but also a specific instances of the resources or our next term we have elasticity one of the best ways to

explain elasticity is to show the user workload off in the typical application during the day where the user workload

changes as the day progresses if you design system like this you need to assign the specific amount resources to

be able to handle the workload properly design system will be able to allocate and deallocate resources whenever needed

if this process is done automatically we are talking about automatic scaling an automatic scaling is basically what

elasticity is summarized elasticity is the ability of the system to scale dynamically our next term is agility in

the cloud there are two ways to provision resources either manually via portal or unabated ways using api's and

scripting but regardless of what choice do you make both cases there's the time between

the request is submitted and the response that the request has been fulfilled and the major difference

between the cloud and on-premises is that requesting resources in on-premises environment usually takes days weeks or

even months in cloud once you request the resource you will most likely get it within seconds or minutes and for very

few very big services this might take few hours but still this is a major difference between the on-premise

environments in this case when we say agility we mean the ability to react quickly and in the cloud this means

being able to allocate and deallocate your resources in very short time the next term on our list is so-called fault

tolerance as a user you purchase services from the cloud whenever that's web application virtual machine or SQL

but regardless of the service that you choose or the interface that you use that service with all those services

need to run on some sort of servers in a data centers storing their data on disk arise whenever there's any service or

component failures on those servers were out on to be moved to another and same goes for discs arise your data is

ultimately stored on multiple discs and multiple disk arrays to ensure no data is lost both tolerance in this case

talks about the ability of the system to remain up and running during component and service failures so those localized

failures will not interrupt your service most of the time in the cloud all the services have built-in fault tolerance

that means if you use cloud services you will not notice those localized failures affecting your system at all besides

those localized failures an event of much greater scale might happen and even like this is called disaster disaster is

a serious disruption of entire service caused by natural or human induced causes a scenarios of this level that we

talk about are typically like floods earthquakes under storms power grid failures or human errors but they can

affect entire arjun region or entire other servers from working properly in this case

to do is set up disaster recovery is aster recovery simply means creating two copies of the same application into our

regions and then setting up replication between them so that you have two identical copies of your application

then in front of those application you need to set up a simple DNS routing so that your users are automatically

redirected to the working version of your application if any service fails they will automatically get resurrected

till replicated version of your application so disaster recovery is system's ability to recover from even

that has taken down entire region or service to simply said it's a way for your system to work properly after a

disaster and our last turn for today is so-called high availability availability is a simple metric that measures how

much uptime of the system so the system being accessible to users or other systems versus how much downtime this

system had in this case downtime means planned occurrences like system downtime for patching or unplanned so system

failures and availability it's a simple calculation between the uptime and entire lifetime of the system and

depending on what you agree with your client you calculate availability barrier month or day using this metric

is very important because ninety-nine percent availability means only three days of downtime per year if you go for

free nights that's only eight hours almost nine hours per year of downtime but most companies targeting high

availability they go for at least four nines which means fifty-two minutes per year

with so restrictive uptime requirements you will need a specific tools and specific design in order to achieve high

availability but in this case summarize availability is a measure of system uptime for either users or services and

high availability basically means ability of the system to run for very extended periods of time with very

little downtime to things that I want to mention here is that one depending on the criticality of your system you need

to choose whenever this system should be highly available or not but luckily for us in our many services

deliver very high availability by default so just check what they offer and decide if the service is right for

you next steps after watching this episode go to my website Marcia Gay Oh 8900 hashtag episode a1 and check out

the materials that I prepared for you especially check out the cheat sheet and practice tests to test your knowledge

and that's it for this episode thank you guys for watching if you like what I do support the channel by subscribing

liking and commenting or showing this to your friends if you want to see the next episode simply follow the playlist or

hit the icon on the side and see you there [Music]