Here and welcome back.
So in today's we we'll be discussing about the placement groups now that are two important features
associated with placement groups that we need to remember.
And these two points summarizes the overall features and the necessity of placement groups.
So the first point, your state that the placement groups are recommending for the applications that
require low latency, high network throughput.
And the second point are states that the placement groups can be used to influence the placement of
the group of AC2.
Two instances that you launching AWG.
So let's do one thing.
Let's go ahead and understand each of these points individually.
And we'll start with the first point dooryard.
Now, the easiest way in which I can give you an explanation or the first point is through this screenshot.
Now this screenshot is a small road on the left and maybe on the right.
Now you can easily imagine what this is.
So if you're driving a vehicle within this small road, then the overall speed through which your vehicle
can go through is much more less then compared to the speed in highway.
So similar to this specific analogy, if you now look into the first point, let's reread it.
So the first point states here that the placemen groups are recommending for the applications that require
low latency, high network throughput.
So any applications that really require the network throughput to be very fast, typically there can
be applications related to the high performance computing, which requires a very high network throughput.
So far, such kind of applications, you can make use of placement groups.
So let's go ahead and understand this in more detail.
So we have one more analog example that can allow us to explain the first point that indeed.
So let's say that this is in the region and there are three availability zones in L.A. Let's assume
that there are three availability zones.
Or, you know, what would happen is that if you have a server in this green availability zone and if
you have a second server in this great availability zone and if you try to communicate between them,
then there will be a certain delay that will happen because the traffic needs to go from green to red
and return back.
So farther the distance, the more it might take for the packet to return back.
Similar to that, the distance between the green and the blue is much more or less so.
The amount of time that it might take for the return traffic will be much more or less so when compared
to the green and the red.
And similar to that, if both of your servers are within the same availability zone of green, then
the speed will be much more faster because now you do not really have to go towards either availability
zone.
The traffic is promising within the same data center.
So that is what is the intention of the first point within the placement.
So what we do here is that we try to launch the service within a placement group in such a way that
it is within the same track or maybe within the same underlying host.
So then the overall capacity in terms of network throughput will be extremely high.
So let's do one thing.
Let's take one more example so that we can have a nice understanding of this point.
So I have a server which is located within the same region of the place where I'm recording.
So when I go ahead and build this server, you will see that the overall deal is 53.
Now, similar to that, if I try to locate Usera like Amazon.com and if I try to pin them, you see
the overall details to 22, which is much more higher than what is compared to the server, which is
located near the place that I am recording.
So this is what Placemen Group tries to offer.
So what it tries to do is that it tries to go locate the servers that you launch as close as possible.
So the idea is that the servers, if they are very close to each other, may be within the same underlying
host or within the same bracket.
Then the amount of data transfer speed will be much more higher.
And that is what the primary aim of the first pointer associated with the placement groups are.
So I'm sure now you understand what the first point that is now, Les Gordon.
I understand the second point that as well.
So the second point states that.
The Placemen Group can also be used to influence placement of a group of Ekta instances.
So let's go ahead and understand this point.
As we know, your concept about virtualization will allow you to understand this point in much more
detail.
So first important point is that a single server can run multiple virtual machines.
So if you have made use of virtual box of VMware or even given, you know that a single server or even
a single laptop can run multiple operating system at once with the help of virtualization.
So this can also be explained with this diagram below where you have a single host here.
So if you see you have a seamless server, and with this help of virtualization, there are multiple
virtual machines which are running.
So these virtual machines in Aders are also quite as they easy to instances.
So a single soda can have multiple AC2 instances.
Now, this point can lead to issue if you're running a cluster of servers.
So let's understand this with an example.
So the example states here that you have a medium called which is an organization and it is running
a MySQL cluster consisting of two servers in a single availability zone, and the server are of by and
for large.
Now it can happen that these two servers, which are running as part of the service equals cluster,
are running on the same host.
So if you'll see that you have a server also there is a virtualization layer and on top of virtualization
layer, there are three servers to among this are of and for light.
So this can happen sort of scenario that if you're launching 2000 same availabilities on both of those
servers or both of the you see two instances can be part of the same underlying hardware.
Now, this kind of a scenario is risky because it can happen that due to some issue with the underlying
hardware, your server is down.
And if the server is down, all the virtual machines which are running on top of it will also fail.
And in such cases, if you look into this example, if this horse has to fail, then both of them,
for instance, which are part of the mystical cluster, will break down and your database would be down
completely.
And this is one of the reasons why it is recommended to always for the Mighty Is, etc. Not even with
single easy.
There are ways in which you can tell to A.W. is that I want to launch to easy two instances in a single
availability zone, but they should not be part of the same server for us.
Seem to be more precise.
So with the help of Placemen Group, you can explicitly specify that two instances should not be part
of the same server or you can sustain Brightcove server.
So now, with the help of Placemen Group, you will see in this diagram you have one M, for instance,
which is being hosted in one server and you have Sarkin in for instance, which is hosted in a second
server.
Now both of these are within the same availability zone, but you can explicitly define that with the
help of placement group.
Now in case a default server goes down, then you also have a second etc etc, which is running in an
entirely different rack so that you are see, so many of you might be familiar with cracks within the
data center.
So this is a typical example of a data center where there are multiple racks of servers which are available.
So what you can tell is the first might be launched in this first track.
The second server might be launched in this specific track.
So even if the indirect has an issue, you also will not face any downtime.
Great.
So with this basic understanding of what the point is, let's look into the types of placement groups.
So there are three types of placement groups available.
The first type is a cluster.
So cluster placement group basically backs instances close to each other within a same availability
zone.
So this can be better understood.
So in this diagram, you see that there are two availability zones, but with the help of Cluster Placement
Group, you try to place both of your instance within the same availability zone.
Or to be more precise, it would be within the same underlying hardware or at least within the same
guy.
So then what would happen is, since the rules are very close to each other, they will be a very high
network throughput that you can achieve so that pipe can be obtained with the help of Cluster Placement
Group.
So let's do one thing, let Gordon understand this in more detail practically so that it is much more
fun for us to learn.
Now, this is the city council and within the city council, if you go back down, there is a tab for
Placemen Group.
If you click on it, you will have a screen similar to this.
So if you click on Create Placemen Group, you will see that there are three types of placemen groups
that you can create for this cluster sickness, prick and transportation.
As we have discussed, the Cluster Placemen Group tries to launch the instance within the same underlying
server or within the same bracket so that the overall network throughput is much more faster.
So that is the type of cluster placemen group.
So let's go ahead and try it out so you can have one cluster.
The strategy is cluster and you can go ahead and create.
So you see it now.
It has gone ahead and created a placement group called Escapology Cluster.
Now, if you go to instances and click on Launch Instant's and let's go ahead and select the latest
IMMI and we use the instance type, lets select and find out.
But now there is a specific reason why we're selecting the instance, which is much more bigger than
that we do micro.
So we'll be discussing about that in a moment.
Let's go to the next screen and you're there is the Option of Placemen group so you can select this
and you can see add to existing placement group and you can select the placement group, you and within
the number of instances, you can see three.
So now what will happen is A.W. will launch this three or four easy two instances within the same underlying
host of which is available, or it will try to launch it as close as possible.
So that is the main aim of that cluster placement group.
Do remember that it needs to be within the same availability zone.
Great.
So that is the first type of placement group.
Second is the partition.
So what happens in a partition placement group is that aid of this ensures that each partition within
the placement group has its own set of tracks.
Now, we have already discussed what tracks are.
So in this diagram you see that there are three partitions and each partition has three Ishita instances.
So when you make use of partition placement group and partition, you can ensure that each of this partition
is running on a separate track altogether.
Now, if you're running in a separate track, then there is a better fault tolerance, because in case
if the rack feels so, in case, let's say the first track fails, then only the server associated with
the first partition will go down.
The other two servers will still be running.
So that is the importance of a partition placement groups.
Now the third type is coalesce the spread placement group.
No evidence Spread Placemen Group.
What happens is that each of the sort that you launch will be running on a different track altogether.
So let's say that there are seven rows which are currently in this diagram.
Then seven servers will be running on seven separate.
Right.
So, for example, let's say that the first row will run, your second server will run your third.
So I will run you at forty fifth, six and seven.
So that is the whole idea about the spread placement group audio.
So your default tolerance is much more higher because when you take an example of partition placement
group, if one track fails, then all the three servers associated with the partition will go down.
However, within the spread placement group, if the one track fails, then only one server will go
down, all the other six will still be running.
So let's do one thing.
Let's go back to the console.
Let's go to Easy Do and we'll go back to placemen groups.
So the first one we already discussed.
Let's go and explore the other one within a year.
Let's take an example.
If you're making use of Partition Placemen Group, so if you remember, you have to select the number
of partition.
So if I select the number of partition is five and if you launch five, you see two instances, then
all the phase two instances will be part of a different rack altogether.
Great.
So I hope with this you got a better understanding of what placemen groups are and also the different
types.
So there are a few important pointers that you need to remember.
The first one is associated with the cluster placement group.
First one is that cluster placement.
You cannot span across multiple availability zones.
We have already discussed that the primary aim of cluster placement is to provide a high network throughput
and the entire purpose gets lost if you're launching it into two distinct availability zones.
So in order to achieve a high throughput, you launch the instances within the same availability zones.
So that is the first point.
Second point is that only a specific type of easy two instances can be launched.
This is because certain types of you see two instances like the two micro DataDot small.
They do not really have a fast network throughput that you can attain.
So there are specific to instance types that you can launch within that cluster placement.
So if I have to quickly show you through the documentation, let's go to the cluster placement group
and we'll go back down.
Now, if you look into the cluster placement group rules and limitation, you will see that there are
only certain instance types that can be launched.
You certainly cannot launch instances.
They'd like to do that micrometeoroid small because then the entire purpose gets lost.
So these are the instance types that you can launch within the cluster placement group.
Again, if you look into the second point of cluster placement group cannot span across multiple availability
zones.
That all important point is that a maximum network throughput traffic between two instances in a placement
group is limited by this lower of two incidents.
So let's say that there are two instances which have Lightford within the placement group.
The first instance is capable of Tenebrous.
The second instance is capable of 20 MBBS.
So the overall network throughput that you can obtain between these two instances would be in, which
is the slope of both of them.
So that is what the third point is on.
The fourth point, which is quite important, is that it is recommended to launch all the instances
together.
Now, when you launch all the instances within the cluster placement group together, then you will
try to keep them as close as possible, typically within the same underlying force as well.
So if you're launching the instance at a later stage, then there can be capacity errors.
So if you're facing capacity errors, the recommended way is to stop and start all the instances in
Placemen group.
So this used to be a classic example question where there is a scenario where someone is trying to launch
more instances within a placement group and there is a capacity error.
So now there will be four options in terms of answers and you'd have to select the right answer to the
right answer is you have to stop all the instances and start it within the placement groups grade.
So we have gone ahead and looked into Placemen Group in great detail.
I hope this video has been informative and I look forward to seeing the next video.