1

00:00:02,960 --> 00:00:09,940

So in this session we are going to learn about setting up Cluster.  In this example I'm going



2

00:00:09,940 --> 00:00:17,200

to take 3 Nodes.  So Node 1,  which is going to be Master node and then there are 2 more Nodes, which are



3

00:00:17,200 --> 00:00:18,990

going to be Slave Nodes.



4

00:00:19,480 --> 00:00:24,990

So in total we have 3 nodes or 3 Servers.  So IP address or Server 1



5

00:00:25,030 --> 00:00:34,710

is 10.128.0.2 and Host name is itpanther01 and then we have Slave Nodes, which is IP



6

00:00:34,710 --> 00:00:43,710

address is 10.128.0.4,  Host name is itpanther02 and then the third Node is 10.128.0.5



7

00:00:43,900 --> 00:00:52,200

and Host name is itpanther03.  So initially when we are going to set up the Cluster. First Node is



8

00:00:52,200 --> 00:00:58,500

going to be Master and then when Master is going down then one of the Slave Nodes is going to be



9

00:00:58,500 --> 00:01:03,320

promoted to Master and  this thing is going to be taken care by Sentinel.



10

00:01:04,210 --> 00:01:04,540

Okay.



11

00:01:04,560 --> 00:01:11,620

So we are going to set up Redis and plus Sentinel on each of these Nodes.



12

00:01:21,740 --> 00:01:30,240

So Sentinel is already bundled with the software,  which you download,  when you download Redis. So if



13

00:01:30,240 --> 00:01:37,650

you remember in our first example,  I had already  downloaded the Software.  So I have that software and then



14

00:01:37,650 --> 00:01:46,970

we are going to extract this software and we will go on to configure.  So before we start configuration.



15

00:01:46,970 --> 00:01:51,200

Just wanted to verify all the IP addresses,  which we have shown here.



16

00:01:51,200 --> 00:01:53,230

So these are the same thing which we have here.



17

00:01:54,020 --> 00:02:00,740

So let me clear the screen and let's begin with verifying the Host name.



18

00:02:03,410 --> 00:02:12,120

So you can verify that first server is itpanther01 and this is the IP address and then I'm going to use



19

00:02:12,180 --> 00:02:16,170

ssh command  to log in to Server or Slave Nodes.



20

00:02:34,840 --> 00:02:40,720

If you use Host name,  it is going to give you the host name of the Server. If you use Host name  -i



21

00:02:40,750 --> 00:02:42,940

It is going to show you the IP address.



22

00:02:43,390 --> 00:02:45,220

So this is one of our Slave Nodes.



23

00:02:49,500 --> 00:02:53,870

and now I'm going to log in to Second Slave Node



24

00:03:01,450 --> 00:03:01,760

okay.



25

00:03:01,790 --> 00:03:05,550

So these are the servers,  which we have and we are able to log into all the servers.



26

00:03:08,530 --> 00:03:14,710

Now also just to show you that initially we do not have any, you know, software available in any of



27

00:03:14,710 --> 00:03:15,480

the Slave Nodes.



28

00:03:15,880 --> 00:03:21,670

So this is the home directory of the  Slave Node and we do not have any software available.



29

00:03:21,670 --> 00:03:29,650

So we are going to copy the software from Master Server to both the Slave Nodes.



30

00:03:29,650 --> 00:03:37,480

So I'm going to clear the screen and let me also exit because right now if you see I'm on Node 3 which



31

00:03:37,480 --> 00:03:43,570

is indicated by here itpanther03. So I will do Exit and I'll be back to server 1



32

00:03:48,110 --> 00:03:48,410

Okay.



33

00:03:48,410 --> 00:03:58,160

Now if we do ls-lrt, we see this is a software which we have downloaded and let me extract this



34

00:03:59,060 --> 00:03:59,600

software



35

00:04:14,280 --> 00:04:14,580

okay.



36

00:04:14,580 --> 00:04:22,560

Now we see Redis-stable folder.  So inside Redis-stable folder



37

00:04:22,710 --> 00:04:30,680

If you do ls-lrt again,  you will see we have Redis.conf  and also we have a



38

00:04:30,690 --> 00:04:32,690

Sentinel.conf. OK.



39

00:04:32,740 --> 00:04:40,150

So Redis.conf is going to be used for all the configuration with respect to Redis and



40

00:04:40,150 --> 00:04:44,650

Sentinel.conf,  is going to be used for all the configuration related to Sentinel



41

00:04:47,500 --> 00:04:49,990

and also if you go inside src folder



42

00:04:55,400 --> 00:04:58,940

and here if you do a ls-lrta



43

00:05:08,560 --> 00:05:12,450

OK initially if you do ls-lrta, you will not see.



44

00:05:12,930 --> 00:05:19,590

you know, Redis-server or Redis-Sentinel utility because this is just the uncompiled



45

00:05:19,580 --> 00:05:20,020

version.



46

00:05:27,310 --> 00:05:29,170

So first we need to compile this.



47

00:05:34,540 --> 00:05:41,720

So right now we are in  Redis-stable  directory.  Let me clear the screen and this is the position



48

00:05:41,790 --> 00:05:43,340

where we are right now.



49

00:05:43,370 --> 00:05:45,980

So we are  Redis-stable folder



50

00:05:46,430 --> 00:05:54,760

And here if you remember,  to make the, to compile this. We need to run Make command.



51

00:05:54,880 --> 00:05:58,520

So run Make command and hit enter.



52

00:05:58,650 --> 00:06:04,530

It is going to take a couple of minutes because it is going to prepare the binaries,  which we are going



53

00:06:04,530 --> 00:06:09,320

to use to run a Sentinel and also Redis server.



54

00:06:32,050 --> 00:06:34,240

So whatever setup we are going to do.



55

00:06:34,240 --> 00:06:36,590

Now it is going to be a production like setup.



56

00:06:37,660 --> 00:06:37,900

OK.



57

00:06:37,900 --> 00:06:40,480

The same thing you can follow in the Production Environment.



58

00:06:57,770 --> 00:07:04,790

So usually what I do is,  I compile the software at one of the  servers and then we do not need to do the



59

00:07:04,790 --> 00:07:07,310

same activity on other servers.



60

00:07:07,310 --> 00:07:10,940

We can just copy paste the  same software.



61

00:07:11,000 --> 00:07:11,270

OK.



62

00:07:11,290 --> 00:07:13,070

which is compiled one.



63

00:07:13,100 --> 00:07:23,250

So now you see it is already,  the software is compiled and we  would have Binaries now.  Lets do



64

00:07:23,320 --> 00:07:31,500

ls-lrt and now if we go inside src folder again and do ls-lrt. This time we can see



65

00:07:31,500 --> 00:07:36,180

we have Redis-server and also we have a Redis-Sentinel.



66

00:07:36,360 --> 00:07:42,390

So Redis-server is  going to be used to start Redis server and also Redis-Sentinel will



67

00:07:42,390 --> 00:07:43,970

be used to start Sentinel.



68

00:07:46,940 --> 00:07:51,050

and both of these you know, utilities accept configuration file.



69

00:07:52,010 --> 00:07:58,520

So Redis-server,  we are going to pass Redis.conf file while starting Redis server and



70

00:07:59,090 --> 00:08:07,130

to Redis-Sentinel, we are going to pass Sentinel.conf file.  So that is why it is important



71

00:08:07,130 --> 00:08:12,260

we set up a Configuration File correctly before starting



72

00:08:12,260 --> 00:08:14,210

both of these services.



73

00:08:14,420 --> 00:08:19,130

So I am going one level back and if we do ls-lrt, here we have



74

00:08:22,050 --> 00:08:24,400

Redis.conf and Sentinel.conf.



75

00:08:24,640 --> 00:08:29,530

So let's start by setting up configuration for Redis.conf



76

00:08:30,500 --> 00:08:35,060

And remember currently we are on the Master Node. So whatever configuration we are doing, it is for the



77

00:08:35,060 --> 00:08:35,690

Master Node.



78

00:08:41,130 --> 00:08:43,920

So I'm opening Redis.conf in VI Editor



79

00:08:52,630 --> 00:08:59,670

and now if you scroll down, first thing we need to change is the buying address.



80

00:09:00,240 --> 00:09:00,490

Okay.



81

00:09:00,490 --> 00:09:04,150

So by default it is showing 127.0.0.1



82

00:09:05,170 --> 00:09:12,460

So this one we need to change to the actual IP address of the server, on which Redis instance is



83

00:09:12,460 --> 00:09:14,080

going to run.



84

00:09:14,080 --> 00:09:18,850

So this is Master Node. So for this one, we need to put the IP address of the Master Node.



85

00:09:25,880 --> 00:09:30,170

So here I have made the change and put the IP address of the Master Node



86

00:09:44,270 --> 00:09:48,330

and the second thing we can also make change in the  log file. So a Log file



87

00:09:48,560 --> 00:09:51,820

Usually I keep at /tmp directory.



88

00:09:51,860 --> 00:09:56,690

So I'm going to give location of /tmp/redis.log



89

00:09:59,630 --> 00:10:06,790

So on the Master Node, under the /tmp directory.  There is going to be a file created Redis.log



90

00:10:06,790 --> 00:10:15,100

that is going to hold all the logs related to Redis database and if you scroll further down,



91

00:10:15,110 --> 00:10:16,070

Now we need to



92

00:10:23,840 --> 00:10:24,110

okay.



93

00:10:24,120 --> 00:10:33,440

So now you can search  Replica of,  but make sure that on the Master Server, you do not make any changes



94

00:10:33,440 --> 00:10:39,310

here in the Replica of. In  the Master Server,  we don't need to make any changes here.



95

00:10:39,350 --> 00:10:46,930

And on the Slave Nodes, we are going to make changes here and going to update the Master IP address and



96

00:10:46,930 --> 00:10:47,810

Port Number here.



97

00:10:48,190 --> 00:10:48,520

Okay.



98

00:10:48,520 --> 00:10:49,000

So



99

00:10:52,590 --> 00:10:54,540

for now on the Master Node, we are done.



100

00:10:54,540 --> 00:10:56,490

We don't need to make any other changes here.



101

00:10:58,350 --> 00:11:05,050

So save and Exit and now let's make changes in the Sentinel.conf File.



102

00:11:08,040 --> 00:11:08,550

so here



103

00:11:08,550 --> 00:11:16,740

also first thing you need to do is, change this Bind Address and by default it is, if it is commented



104

00:11:16,760 --> 00:11:17,960

you can uncomment



105

00:11:21,480 --> 00:11:25,690

and remove whatever default IP addresses are given.



106

00:11:25,700 --> 00:11:32,500

And since we are making Configuration on muster.



107

00:11:33,140 --> 00:11:36,260

So here we need to be the IP address of the Master.



108

00:11:48,070 --> 00:11:48,380

okay.



109

00:11:48,410 --> 00:11:54,320

So the IP address for that is 10.128.0.2



110

00:11:54,390 --> 00:11:55,740

This is a very important step.



111

00:11:55,830 --> 00:11:59,400

So always make sure we have the correct IP address updated here.



112

00:11:59,940 --> 00:12:02,890

Otherwise your Redis server or



113

00:12:03,000 --> 00:12:10,050

and also you're Redis Sentinel may not be able to communicate with each other with Slave Nodes.



114

00:12:10,170 --> 00:12:10,460

Okay.



115

00:12:10,470 --> 00:12:17,760

So that is going to be very complicated, once you end up into issues and it is going to be very difficult



116

00:12:17,760 --> 00:12:21,790

to troubleshoot,  especially when you are doing it for the first time.



117

00:12:21,840 --> 00:12:25,650

So always make sure you have the correct IP address updated in the Bind



118

00:12:31,230 --> 00:12:37,480

and for Sentinel,  I'm going to change the log file to /tmp/sentinel.log



119

00:12:41,720 --> 00:12:50,270

If you have seen, we have not made any changes in the port. So default Port for Redis is 6 3 7 9 and



120

00:12:50,270 --> 00:12:55,240

for Sentinel it is 2 6 3 7 9.  Okay.



121

00:12:55,270 --> 00:12:56,590

So this is going to be same



122

00:13:00,900 --> 00:13:01,830

on all the nodes



123

00:13:08,820 --> 00:13:09,110

okay.



124

00:13:09,120 --> 00:13:13,200

Now we have made the basic changes which was required on the



125

00:13:16,660 --> 00:13:19,140

Master Node.



126

00:13:19,230 --> 00:13:20,580

I think I'm missing one thing here.



127

00:13:20,610 --> 00:13:22,730

So let's go to Sentinel.conf file



128

00:13:22,800 --> 00:13:30,110

again and here I think we missed one thing,  which was related to Sentinel Monitor.



129

00:13:30,270 --> 00:13:30,570

Okay.



130

00:13:30,570 --> 00:13:32,850

So this is again important thing here.



131

00:13:32,880 --> 00:13:40,100

You specify the IP address of your Master Node.



132

00:13:40,100 --> 00:13:47,910

So here we know Master node is going to be 10.128.0.2 and this is the Master Node which



133

00:13:47,910 --> 00:13:53,850

is going to be the Initial Master Node.  After that Sentinel is going to decide on its own that and



134

00:13:54,060 --> 00:14:03,640

Sentinel is going to elect a new master in case existing master goes down and after the IP address we



135

00:14:03,640 --> 00:14:04,870

have Port number.



136

00:14:05,170 --> 00:14:11,050

So as we know,  we have not made any changes and default Redis runs on 6 3 7 9.



137

00:14:11,080 --> 00:14:17,110

So the  same port is given here as well and this name My Master Name is the logical name.  If you want to



138

00:14:17,110 --> 00:14:19,200

change it, it can be changed as well.



139

00:14:19,300 --> 00:14:21,070

In my case I'm not going to change it.



140

00:14:23,880 --> 00:14:28,440

However, when you are doing the same thing in the Production, based on the Organization Naming Structure



141

00:14:28,440 --> 00:14:30,690

or Naming Standards, you may need to change this.



142

00:14:33,960 --> 00:14:42,670

and after the Port, we have the count of the Quorum which is set to number 2. So the count of the Quorum



143

00:14:42,740 --> 00:14:49,120

specify,  this is the minimum number of Sentinel Nodes,  which need to agree, whenever they are going to



144

00:14:49,120 --> 00:14:50,230

make any decision.



145

00:14:50,680 --> 00:14:56,460

So the decision can be that whether the Master is down or not.



146

00:14:56,550 --> 00:15:01,230

And  which of the  Slave Node, should become the new Master.



147

00:15:01,470 --> 00:15:09,770

Okay so these are the decisions which Sentinel is going to make and minimum of 2 sentinel servers



148

00:15:09,780 --> 00:15:17,520

has to agree in order to make one of the existing Slave and promoted into a Master.



149

00:15:24,940 --> 00:15:29,740

So when you make any changes here with respect to the name My Master.



150

00:15:29,740 --> 00:15:35,610

So make sure you also need to make  changes for the same name in the other lines as well.



151

00:15:35,620 --> 00:15:39,810

So this name, whatever name you give here should also be matching in the other name.



152

00:15:41,300 --> 00:15:45,560

Which you can see here, like it is set up here or here.



153

00:15:45,560 --> 00:15:51,970

In my case I have not made any changes. Okay so that's why I don't need to make any changes in the



154

00:15:51,970 --> 00:15:53,690

names.



155

00:15:53,710 --> 00:15:58,420

Now the other important thing is, here you see Sentinel down after milliseconds



156

00:16:01,300 --> 00:16:03,610

and here you specify the name of the Master Node.



157

00:16:03,640 --> 00:16:10,360

So basically here we are telling that after how many seconds Sentinel is going to say that



158

00:16:10,390 --> 00:16:17,230

Okay Master node is down and it is going to work towards promoting one of the Slave Nodes to make them



159

00:16:17,320 --> 00:16:19,480

a Master. okay.



160

00:16:19,490 --> 00:16:26,590

So by default it is set to 30000 milliseconds which is equal to 30 seconds.



161

00:16:27,160 --> 00:16:33,780

So again depend on the design  which you want to set up in the Production Environment.



162

00:16:33,780 --> 00:16:37,280

You may increase or decrease the value here.



163

00:16:37,320 --> 00:16:40,920

Right now we are just going to leave it to default which is 30 seconds



164

00:16:44,290 --> 00:16:45,970

okay so that's it here.



165

00:16:46,000 --> 00:16:47,170

Now I think we are good.



166

00:16:48,520 --> 00:16:56,700

So I have saved and exited from here. Okay so we have done the kind of basic configuration for this node.



167

00:16:56,760 --> 00:16:59,600

Now I'm going to copy the software to the other nodes.



168

00:17:02,010 --> 00:17:08,320

And also make sure once you copy the software to  other nodes,



169

00:17:09,330 --> 00:17:12,480

You need to make changes related to the IP address on the other nodes.



170

00:17:13,290 --> 00:17:15,750

Okay so let's see that.



171

00:17:15,860 --> 00:17:19,540

Let me clear the screen first and go one step back.



172

00:17:21,410 --> 00:17:24,320

So I'm going to use scp command.



173

00:17:24,320 --> 00:17:24,820

So scp command



174

00:17:24,890 --> 00:17:29,120

is used to transfer files from one server to another server.



175

00:17:29,990 --> 00:17:36,140

So in this case I want to copy this complete directory.  So that's why I have given scp -r which



176

00:17:36,140 --> 00:17:46,690

is recursive and then we need to specify the server, where we want to copy this, you know, directory or files.



177

00:17:46,720 --> 00:17:53,640

So in this case it is going to be  itpanther02, which is one of the Slave Nodes.



178

00:17:53,680 --> 00:17:59,350

You can also specify the IP address but usually it is easier to specify the Host name



179

00:18:04,250 --> 00:18:11,560

and then this ~/  is actually specifying that, we need to copy this Redis-stable



180

00:18:11,570 --> 00:18:12,800

to the home directory



181

00:18:16,690 --> 00:18:17,000

okay.



182

00:18:17,020 --> 00:18:18,130

So on this Server



183

00:18:20,810 --> 00:18:24,730

Redis Admin's home  directory. This Redis-stable is going to get copied.



184

00:18:25,290 --> 00:18:26,630

Okay so let's hit enter.



185

00:18:32,820 --> 00:18:33,160

okay.



186

00:18:33,160 --> 00:18:40,770

So yeah we missed to specify the directory,  which we want to copy.  So that's why we got the error



187

00:18:40,960 --> 00:18:48,780

So this is the correct syntax. So use give scp -r  the directory, which you want



188

00:18:48,780 --> 00:18:56,850

to copy along with the sub-directories and files and then you give that Host name,  from where you want to



189

00:18:56,850 --> 00:19:04,780

copy and also if you want to copy under any other user,  you can also specify that User Name here.



190

00:19:05,110 --> 00:19:13,470

Whatever User Name you want to copy it to.  If you do not specify any user here, on the server where you



191

00:19:13,470 --> 00:19:17,820

are trying to copy.  This software it is going to copy the same user name.



192

00:19:18,020 --> 00:19:18,280

Okay.



193

00:19:18,300 --> 00:19:24,300

So in this case I already have Redis Admin user name created on all the Slave nodes as well.  So



194

00:19:24,300 --> 00:19:31,700

we may not need to specify the User Name here.  Again so the fundamental here is, that we are copying this



195

00:19:31,780 --> 00:19:39,290

Redis -stable software from Master Nodes to  Slave Nodes. You may use WinSCP or any other



196

00:19:39,290 --> 00:19:42,300

mechanism to copy this software from one server to another.



197

00:19:42,440 --> 00:19:46,700

So I'm just using SCP here and let's hit enter.



198

00:19:49,750 --> 00:19:54,660

Now the File Copy is in progress and File Copy has been completed.



199

00:19:58,710 --> 00:20:05,140

Now let's also copy this software on Third Node, which is itpanther03. So I have changed  the host name



200

00:20:05,160 --> 00:20:09,210

here, remaining all. Everything remains the same.



201

00:20:09,210 --> 00:20:09,750

Hit Enter.



202

00:20:17,770 --> 00:20:20,770

Okay so now software has been copied.



203

00:20:20,770 --> 00:20:27,000

Now we will log in one by one to the Slave Nodes and also we will correct the configuration changes



204

00:20:27,010 --> 00:20:28,960

which we have set up for Master Node.



205

00:20:29,590 --> 00:20:32,240

Okay so Master Node is done.



206

00:20:32,290 --> 00:20:36,460

Now let's log into Slave Node, which is itpanther02



207

00:20:41,000 --> 00:20:47,030

and here if I do a ll or ls-lrt. You can do whatever command you like.



208

00:20:47,030 --> 00:20:51,260

And now we can see, we have Redis-stable folder  here.



209

00:20:51,260 --> 00:20:57,940

So if we go inside Redis-stable and we open,



210

00:20:58,320 --> 00:21:09,040

Redis.conf. Okay the same thing whatever configuration which we have done on Master node,  has been



211

00:21:09,040 --> 00:21:10,940

copy pasted here on the other nodes.



212

00:21:11,710 --> 00:21:16,270

However, as we know this is itpanther02



213

00:21:16,270 --> 00:21:19,500

So here this IP address is going to be different.



214

00:21:19,560 --> 00:21:19,830

Okay.



215

00:21:19,840 --> 00:21:23,180

So in the Bind, make sure you have the correct IP address.



216

00:21:23,350 --> 00:21:28,160

So this IP address should be,  the IP address on which you are going to run this



217

00:21:28,210 --> 00:21:29,730

Redis instance.



218

00:21:29,770 --> 00:21:30,030

Okay.



219

00:21:30,070 --> 00:21:38,200

So in this case it is going to be 10.128.0.4, because this is server itpanther02



220

00:21:43,750 --> 00:21:50,890

and the benefit we got from making the Configuration, Basic Configuration,  initially and then copy pasting



221

00:21:50,890 --> 00:21:58,450

on other node is, that here we will, we see we already have a Log File specified.  We do not need to, you know,



222

00:21:58,540 --> 00:22:00,830

make the same changes here as well.



223

00:22:01,810 --> 00:22:08,800

So the only change we needed to make was, related to bind and the other thing is, we also need to make



224

00:22:08,800 --> 00:22:12,010

a change in the  replica of.



225

00:22:12,040 --> 00:22:17,130

So on the Master Node,  we have not touched this section.



226

00:22:17,570 --> 00:22:23,550

However when you are working on the Slave Node, you need to provide the Master IP address, in the



227

00:22:23,550 --> 00:22:26,510

Replica of  section.



228

00:22:26,680 --> 00:22:27,480

Okay.



229

00:22:27,790 --> 00:22:36,280

So here we know our Master is running on, 10.128.0.2 and also it is running on default port which



230

00:22:36,280 --> 00:22:39,420

is 6 3 7 9



231

00:22:44,470 --> 00:22:44,770

okay.



232

00:22:44,800 --> 00:22:46,080

So that's it.



233

00:22:46,090 --> 00:22:52,840

We can now save it and exit and now let's make changes in Sentinel.conf



234

00:22:57,160 --> 00:22:59,150

Again first thing is you need to change



235

00:22:59,160 --> 00:23:08,920

Bind Address. Since this software is going to run on server 4. So I have changed it  to, change the IP address



236

00:23:08,920 --> 00:23:12,710

accordingly and Log File,



237

00:23:12,720 --> 00:23:19,270

we don't need to make any changes. So on this server again Log is going to be stored under /tmp



238

00:23:19,270 --> 00:23:28,410

So now we have kind of standard. So across all the nodes including Master and the Slave Nodes, Redis



239

00:23:28,420 --> 00:23:38,730

Logs and Sentinel Logs are going to be stored inside  /tmp directory.



240

00:23:38,800 --> 00:23:46,580

Also if you now see, in Sentinel we already have, you know correct configuration because whatever we did



241

00:23:46,580 --> 00:23:50,670

in the case of Master, the same thing has to be done on the other node.



242

00:23:50,780 --> 00:23:53,280

So we do not need to make any changes here.



243

00:23:59,530 --> 00:23:59,840

Okay.



244

00:23:59,870 --> 00:24:07,580

So the only change which we have made in Sentinel.conf File   is, we have changed the Bind Address and also



245

00:24:07,580 --> 00:24:09,890

provided  the correct IP address of this server.



246

00:24:10,440 --> 00:24:18,600

And now we can save and exit. Okay so now we have done the configuration on Slave Node as well.



247

00:24:18,730 --> 00:24:21,180

Now let's move on to the second Slave Node



248

00:24:25,720 --> 00:24:36,380

So I'm going to do ssh  itpanther03 and now if we do ll, we can see we have the directory



249

00:24:36,380 --> 00:24:36,620

here.



250

00:24:36,620 --> 00:24:38,840

Let's go on to this directory.



251

00:24:42,110 --> 00:24:43,130

and let's



252

00:24:43,300 --> 00:24:45,040

Make the changes in Redis.conf



253

00:24:52,720 --> 00:24:58,810

So here in the bind, please provide the correct IP address of this server which is, in my case going to



254

00:24:58,810 --> 00:25:05,370

be 10.128.0. 5 because this is server 3



255

00:25:10,720 --> 00:25:16,360

Oh, I'm sorry.  It has to be changed to 5. Ok



256

00:25:16,380 --> 00:25:17,540

You can see here.



257

00:25:18,870 --> 00:25:23,580

So this is the Host name and this is IP address.



258

00:25:23,580 --> 00:25:25,380

So the same I have copy pasted here.



259

00:25:31,760 --> 00:25:33,800

Log file is going to remain same.



260

00:25:33,800 --> 00:25:35,450

We don't want to make any changes here.



261

00:25:37,710 --> 00:25:43,520

And now we need to make changes near the replica of section.



262

00:25:43,520 --> 00:25:45,110

So here I'm going to uncomment



263

00:25:48,690 --> 00:25:57,810

and let's provide the master IP address which is 10.128.0. 2 and the port on which master is running



264

00:25:58,440 --> 00:26:05,330

is the default port which is 6 3 7 9.Okay.



265

00:26:05,330 --> 00:26:05,900

So that's it.



266

00:26:05,960 --> 00:26:12,030

Now we can save and exit and now let's make changes in

Sentinel.conf



267

00:26:13,920 --> 00:26:18,720

Here the only change,  which we need to make is,  we need to change this Bind Address to point to the correct



268

00:26:18,720 --> 00:26:19,430

IP address.



269

00:26:19,620 --> 00:26:25,020

So it is going to be 10.128.0. 5. Save and exit



270

00:26:28,460 --> 00:26:28,760

okay.



271

00:26:28,780 --> 00:26:30,880

So from configuration wise we are good.



272

00:26:30,880 --> 00:26:32,880

We have done all the configuration.



273

00:26:33,190 --> 00:26:34,500

So just a quick recap.



274

00:26:34,540 --> 00:26:37,190

We have downloaded the software on Node 1.



275

00:26:37,270 --> 00:26:45,950

Then we did some initial configuration on Node 1, Redis.conf and Sentinel.conf and then



276

00:26:45,950 --> 00:26:54,970

we copy the same software to other Slave Node and we also change the Bind Address to point to the correct



277

00:26:54,970 --> 00:27:00,950

IP address on both the configuration file,  which is Redis.conf and Sentinel.conf



278

00:27:00,970 --> 00:27:09,270

Now we are going to start Redis  on all the nodes. So let me go to Node 1



279

00:27:17,290 --> 00:27:18,600

OK let me clear the screen.



280

00:27:18,700 --> 00:27:22,260

So Host name and Host name-i



281

00:27:22,990 --> 00:27:25,210

So you can see right now we are on the Master Node



282

00:27:28,840 --> 00:27:34,040

and we are here at this directory /home/redisadmin.



283

00:27:34,040 --> 00:27:35,750

So let's start Redis Server



284

00:27:39,310 --> 00:27:42,170

by using command Redis-server and then



285

00:27:45,020 --> 00:27:48,320

we need to pass the Redis.conf file here.



286

00:27:53,230 --> 00:27:57,850

And also I will use & because I want to run this service as a background service



287

00:28:01,630 --> 00:28:02,340

so that's it.



288

00:28:02,380 --> 00:28:03,410

Hit enter.



289

00:28:04,150 --> 00:28:08,080

And also now we can run  Sentinel by using Redis-sentinel



290

00:28:12,050 --> 00:28:18,790

and here we need to provide full path  of Sentinel.conf, use &



291

00:28:18,800 --> 00:28:21,900

Hit enter. Okay.



292

00:28:21,930 --> 00:28:30,660

So now if you want to see the logs of  Redis server and Redis Sentinel, you can go on to  tmp directory.



293

00:28:30,690 --> 00:28:38,880

So we know that we have stored logs at,  tmp/redis.log



294

00:28:39,430 --> 00:28:39,670

Okay.



295

00:28:39,690 --> 00:28:46,450

So Redis logs are this directory. So, I'm using tail to see the logs.



296

00:28:46,620 --> 00:28:50,780

Okay so we can see it is saying that it is Ready to accept connections.



297

00:28:50,780 --> 00:28:59,930

So seems Master has started properly and we can also verify the same  by checking for sentinel.log



298

00:29:02,540 --> 00:29:02,840

okay.



299

00:29:02,870 --> 00:29:04,890

So here also it  seems to be okay.



300

00:29:10,750 --> 00:29:17,030

So on Node 1,  we have started Redis and also Sentinel.



301

00:29:17,130 --> 00:29:19,590

Now I'm going to move on to Node 2



302

00:29:25,460 --> 00:29:32,880

and here also we will start Redis and also Sentinel.  So everything will remain the same.



303

00:29:43,120 --> 00:29:47,890

Just make sure when you are starting Sentinel, you use Redis-sentinel.



304

00:29:47,890 --> 00:29:49,510

Do not use Redis-server.



305

00:29:57,240 --> 00:29:57,610

okay.



306

00:29:57,620 --> 00:30:07,120

So we have started on Slave Node as well.  Let's check the logs by doing tail-f, tail space -f



307

00:30:07,880 --> 00:30:11,780

and going to /tmp/. For Redis Log



308

00:30:11,780 --> 00:30:16,980

we need to go to Redis.log



309

00:30:17,000 --> 00:30:23,630

All right so here now we see, when we started Slave node,  we could see that it is saying,  Master and Replica



310

00:30:23,660 --> 00:30:25,150

has synced.



311

00:30:25,250 --> 00:30:32,020

So basically when we started a Slave node, it was able to connect to Master node and they were Master



312

00:30:32,020 --> 00:30:41,250

and you know,  Slave  were able  to connect and Master was able to replicate all the data from Master to Slave



313

00:30:41,250 --> 00:30:41,900

node.



314

00:30:42,360 --> 00:30:44,960

So this looks fine to me.



315

00:30:45,240 --> 00:30:46,830

Now we can see the log of



316

00:30:49,820 --> 00:30:50,480

Sentinel.



317

00:30:54,980 --> 00:31:04,240

So here also we can see that it has added the child node,  which is slave node to



318

00:31:04,260 --> 00:31:05,960

10.128.0.4



319

00:31:06,010 --> 00:31:11,650

This is a node, which we started and  Sentinel has detected that one more node has been added to the



320

00:31:12,460 --> 00:31:13,290

Redis Cluster.



321

00:31:16,200 --> 00:31:17,790

OK so this also looks good.



322

00:31:25,540 --> 00:31:28,590

And now we can do the same thing on server 3.



323

00:31:28,600 --> 00:31:43,360

So I will clear the screen and let me log into Server 3, which is  itpanther03 and IP address is



324

00:31:43,360 --> 00:31:45,260

10.128.0.5



325

00:31:45,750 --> 00:31:46,070

Okay.



326

00:31:46,070 --> 00:31:48,730

And now we need to start Redis.



327

00:31:59,550 --> 00:32:01,350

now we need to start Sentinel.



328

00:32:12,660 --> 00:32:17,130

Okay just be careful when you are doing for the first time. Do it slowly.



329

00:32:17,130 --> 00:32:22,560

Especially when you are doing on the Production Environment. Okay.



330

00:32:22,580 --> 00:32:27,230

So here also we have started Redis and we have also started Sentinel. So let's see the logs.



331

00:32:36,100 --> 00:32:46,030

Okay on this note also everything seems to be okay and Master and Replica both synced and  both looks



332

00:32:46,030 --> 00:32:47,020

to be in good shape.



333

00:32:49,000 --> 00:32:51,750

Let's check the logs of Sentinel.



334

00:32:58,170 --> 00:32:58,430

okay.



335

00:32:58,450 --> 00:33:02,080

So here also we can see everything is looking okay.



336

00:33:03,490 --> 00:33:11,170

And you can see there is one entry, which is saying +Slave which means Sentinel has detected that one more Slave



337

00:33:11,220 --> 00:33:12,760

has been added to the Cluster.



338

00:33:12,790 --> 00:33:13,080

Okay.



339

00:33:13,100 --> 00:33:15,700

Which is you can verify the IP address.



340

00:33:15,700 --> 00:33:16,990

So now we have two Slaves.



341

00:33:20,760 --> 00:33:27,000

one is 10.128.0.4,  the other one is 10.128.0.5



342

00:33:30,890 --> 00:33:31,520

okay.



343

00:33:31,620 --> 00:33:42,600

So now, right now I'm still on Node 3, which is, you can verify by using Host name  -i



344

00:33:42,600 --> 00:33:51,570

you see the IP address and now to connect to Redis Client, now we need to use Redis-cli



345

00:33:51,780 --> 00:34:01,390

and you know you don't need to switch over to servers by using, Redis-cli. You can pass the



346

00:34:01,600 --> 00:34:05,750

Host name to which you want to connect to and also you can specify the Port.



347

00:34:05,800 --> 00:34:10,760

Okay so if I want to connect to Master Node, I can specify



348

00:34:10,760 --> 00:34:19,000

Redis-cli-h and IP address of the Master Node. So -h signifies Host here.



349

00:34:19,010 --> 00:34:33,380

So we know our Master is running on 10.128.0.2 and it is running on Port 6 3 7 9. So



350

00:34:33,380 --> 00:34:40,670

that's how we connect to you know, from  one of the the client, we can connect to any number of Redis



351

00:34:40,670 --> 00:34:44,200

server. We just need to provide the Host name and the correct Port number.



352

00:34:47,250 --> 00:34:55,980

So right now we are connected to Master Node and let's see since this is a new Setup, we should not have



353

00:34:55,980 --> 00:35:04,200

any data here. As we can see dbsize giving value of 0. If we do Keys * we get empty list.



354

00:35:04,200 --> 00:35:06,500

So basically right now there is nothing



355

00:35:06,830 --> 00:35:08,040

in our Redis Cluster.



356

00:35:09,690 --> 00:35:16,440

Let me exit from here and let's connect to one of the Slave Nodes. So Slave Nodes are running on Node



357

00:35:16,470 --> 00:35:17,270

4 and 5.



358

00:35:17,280 --> 00:35:23,870

So I have changed the IP address and here also we can verify the same.



359

00:35:26,430 --> 00:35:28,130

Okay we do not see any data here



360

00:35:30,980 --> 00:35:33,050

and you can verify the same one Node 5



361

00:35:41,330 --> 00:35:41,630

okay.



362

00:35:41,660 --> 00:35:43,520

So everything is good now.



363

00:35:43,520 --> 00:35:46,460

Now let's connect to Master node again.



364

00:35:46,460 --> 00:35:53,030

So I'm going to provide IP address of Master node and now we will write some data and we should be able



365

00:35:53,030 --> 00:35:57,030

to see this data on the Slave Nodes.



366

00:36:01,590 --> 00:36:03,540

So I will do L push.



367

00:36:03,540 --> 00:36:06,150

I will provide some Color values.



368

00:36:13,460 --> 00:36:20,440

Okay hit enter.  So we have a set up 5 values or we have actually written a key with 5 values.



369

00:36:21,230 --> 00:36:21,670

Okay.



370

00:36:21,690 --> 00:36:32,470

If I do L range, key name 0 -1. I see all the 5 values here on the Master Node. Now lest's connect



371

00:36:32,470 --> 00:36:39,150

to Slave Nodes and let's verify the same.  Okay whether the data has replicated or not.



372

00:36:39,150 --> 00:36:40,890

So I'm going to connect to Node 4



373

00:36:45,130 --> 00:36:45,860

and here.



374

00:36:45,870 --> 00:36:53,760

If we do L range, key name,  which is Color. Starting position is 0. Ending position is -1, which means



375

00:36:53,760 --> 00:37:00,670

it is going to give us all the value of this List and we can see on the Slave Node also,  we get



376

00:37:00,670 --> 00:37:02,860

the same output.



377

00:37:02,980 --> 00:37:04,920

Let's connect to other slave node.



378

00:37:11,510 --> 00:37:12,090

okay here



379

00:37:12,150 --> 00:37:14,180

also, we can verify.  We get the same output.



380

00:37:14,780 --> 00:37:21,180

So it means Redis cluster has been set up properly and master and slaves are in sync.



381

00:37:21,440 --> 00:37:29,690

And whatever we write to Master,  we are able to, Master is able to replicate to all the Slave Nodes.



382

00:37:29,700 --> 00:37:33,500

Now what happens when you try to write anything on the



383

00:37:33,500 --> 00:37:33,710

Slave Nodes.



384

00:37:33,730 --> 00:37:35,980

So right now we are still logged into the Slave node.



385

00:37:36,020 --> 00:37:44,420

And if I do set and some key name, let's say  Product and we specify Chair. Hit enter.



386

00:37:44,420 --> 00:37:52,560

You see we get error that It is only a Read Only Node. we cannot write any data to Slave Nodes.



387

00:37:52,560 --> 00:37:56,570

So this also proves that this is a Slave Node, which we are connected to.



388

00:37:56,790 --> 00:38:01,120

Now I'm going to exit from here.  Clear the screen.



389

00:38:01,120 --> 00:38:05,160

Now we will learn the way how to connect to Redis Sentinel.



390

00:38:06,630 --> 00:38:10,950

So for this one, you still use Redis-cli utility



391

00:38:14,120 --> 00:38:16,610

and you use -h to specify the Host name.



392

00:38:16,610 --> 00:38:22,610

Since we are running Sentinel on all the 3 nodes.  So you can connect to any of the 3 nodes by



393

00:38:22,610 --> 00:38:27,930

specifying the -h and correct Host name.



394

00:38:27,960 --> 00:38:28,210

Okay.



395

00:38:28,230 --> 00:38:37,450

So let's say we want to connect to 10.128.0.2, which is you know, the server where our Master



396

00:38:37,470 --> 00:38:38,810

Redis is running on.



397

00:38:39,060 --> 00:38:49,020

And also we need to specify the Port we are using -P and Sentinel runs on Port 2 6 3 7 9, by default.



398

00:38:49,020 --> 00:38:56,280

And we haven't made any changes.  So we can connect to Sentinel by using  Port 2 6 3 7 9.  In case you have



399

00:38:56,280 --> 00:38:57,170

made any changes.



400

00:38:57,180 --> 00:39:00,370

So you need to specify the correct Port number here.



401

00:39:00,720 --> 00:39:02,110

So hit enter.



402

00:39:02,250 --> 00:39:04,410

Now we are connected to Sentinel.



403

00:39:04,890 --> 00:39:15,030

So there are many commands related to Sentinel,  which you can use to monitor or do various other actions



404

00:39:15,720 --> 00:39:16,880

In this one we,



405

00:39:16,950 --> 00:39:23,310

since this session is all about setting up clusters.  So we are just going to stick to setting up Cluster



406

00:39:23,460 --> 00:39:26,730

and we will just use couple of commands of Sentinels.



407

00:39:27,360 --> 00:39:33,930

So here if you want to see what is, you know, information. So you use Sentinel



408

00:39:37,340 --> 00:39:44,210

space Master and specify the logical Master node. So if you remember in Redis.conf,  we had a



409

00:39:44,210 --> 00:39:48,170

name, which is called My Master and we hadn't made any changes there.



410

00:39:48,200 --> 00:39:52,840

So logical name is going to remain the same, which is going to be called My Master.



411

00:39:53,450 --> 00:39:54,890

So this is  our Cluster Name



412

00:39:57,850 --> 00:39:58,470

you know you can,



413

00:39:58,500 --> 00:40:03,440

Yeah you can take it as a Logical Cluster Name but actually it is pointing to the Master.



414

00:40:04,060 --> 00:40:04,300

Okay.



415

00:40:04,310 --> 00:40:05,350

So if you  hit enter



416

00:40:12,090 --> 00:40:16,860

Now you can see all the information, which is provided by Sentinel.



417

00:40:16,890 --> 00:40:25,900

So right now if you see, Sentinel knows that you know, name of the Master is My Master and it is running on IP



418

00:40:25,930 --> 00:40:30,820

10.128.0.2 and the port on which it is running is this



419

00:40:33,750 --> 00:40:37,130

and the runid  is also provided here.



420

00:40:37,420 --> 00:40:43,750

And the more important thing, if you scroll down, you can see on Line number 21, that we have down after



421

00:40:43,750 --> 00:40:50,730

milliseconds, which is set to 30000 milliseconds, which is equal to 30 seconds.



422

00:40:50,830 --> 00:41:00,190

And also if you look at bit down, you can see the total number of Slaves is shown as 2.  So  Sentinel



423

00:41:00,200 --> 00:41:06,510

is correctly able to  figure out, that how many Master Node or how many Slave Nodes are connected.



424

00:41:06,510 --> 00:41:11,610

So it has shown 1 Master Node at the top and it also knows that there are 2 Slave Nodes, which are



425

00:41:12,140 --> 00:41:20,700

you know, part of this Cluster and also on Line number 33, you can see it is talking well number of other



426

00:41:20,860 --> 00:41:21,660

Sentinels.



427

00:41:22,040 --> 00:41:28,400

So not only Sentinel knows that how many Master and Slave Nodes are running. This also knows how many different



428

00:41:28,940 --> 00:41:34,920

Sentinels are running. So other than this Sentinel,  it also know that there are 2 more Sentinels are



429

00:41:35,020 --> 00:41:38,420

running. Okay and number of Quorums are specified as 2



430

00:41:39,590 --> 00:41:46,250

So it means there are 2 Sentinels instances they have to agree.



431

00:41:46,430 --> 00:41:53,880

You know whenever  one of the Master is down and then they are going to elect a New Master from one



432

00:41:53,880 --> 00:41:56,960

of the existing Slaves.



433

00:41:57,020 --> 00:41:57,320

Okay



434

00:42:04,550 --> 00:42:07,430

so now let's exit from here.



435

00:42:07,460 --> 00:42:21,080

So if you see now, we are on Master node and here let's.



436

00:42:21,590 --> 00:42:21,810

Yeah.



437

00:42:21,810 --> 00:42:27,750

So what I will do now, we will shut down the Master Node services of Redis on Master node and we will



438

00:42:27,750 --> 00:42:33,570

see how Sentinel is going to detect that Master Node is down and it is going to promote a New Node,



439

00:42:34,260 --> 00:42:36,390

you know one of the Slave Nodes to the Master Node.



440

00:42:39,760 --> 00:42:42,070

So first thing is we would like to see the Logs.



441

00:42:42,160 --> 00:42:42,410

Okay.



442

00:42:42,400 --> 00:42:48,060

While this is happening. So let's log into one of the Slave Nodes.



443

00:42:58,740 --> 00:42:59,020

okay.



444

00:42:59,020 --> 00:43:03,580

This is a Slave Node and here we will open Sentinel Logs.



445

00:43:03,640 --> 00:43:10,110

So when we are shutting down services on Master node, we should be able to see the logs in the real time.



446

00:43:10,120 --> 00:43:12,320

so we know what is happening behind the scene.



447

00:43:12,560 --> 00:43:20,420

Okay so we know our Sentinel Logs are stored at /tmp/sentinel.log



448

00:43:20,710 --> 00:43:25,500

And if you hit enter,  you can see the Logs.Okay.



449

00:43:25,500 --> 00:43:27,270

Now I'm going to open a new instance



450

00:43:33,150 --> 00:43:33,520

okay.



451

00:43:33,560 --> 00:43:39,090

So basically this is again the Masters,



452

00:43:39,130 --> 00:43:47,830

Master node and I had just opened a new session.  So you can verify the same using Host name -i



453

00:43:48,050 --> 00:43:59,380

And this is the IP address of the master node.  So here we are going to shut down the services of a Master



454

00:43:59,380 --> 00:44:04,150

Node.  So now there are two ways to shut down Master Node. If you want to shut down the services,



455

00:44:04,300 --> 00:44:11,590

Redis services gracefully. You can use Redis-cli and you can provide the name which is



456

00:44:11,580 --> 00:44:18,740

10.128.0.2 and provide the Port number, which is 6 3 7 9.



457

00:44:18,740 --> 00:44:22,850

And here you can write the command which is called Shut Down.



458

00:44:23,190 --> 00:44:32,190

Okay so it is going to shut down the Master Node.  However since this is not a you know,  we want to simulate



459

00:44:32,880 --> 00:44:39,450

a Production scenario and typically in a Production scenario service will, service may go down abruptly,



460

00:44:39,480 --> 00:44:42,000

when the server goes down.



461

00:44:42,000 --> 00:44:47,370

So we can just use ps-ef  command to kill the Redis service



462

00:44:52,010 --> 00:45:01,850

So here we can see that this server is running on Port 6 3 7 9 and this is a process ID.  So I will



463

00:45:01,850 --> 00:45:06,910

use kill command.  kill -9 and the process ID.



464

00:45:06,920 --> 00:45:15,820

So this is going to kill  Redis Master Node. So once you do that, within 30 sec, we should be able to see



465

00:45:16,200 --> 00:45:21,940

you know, some changes happening here and Sentinels should be able to detect that Master is down and



466

00:45:21,940 --> 00:45:28,550

it should be able to promote one of the existing Slave Nodes to a Master Node.  So let's see how this



467

00:45:28,550 --> 00:45:28,940

works.



468

00:45:30,410 --> 00:45:31,290

So I'm back here.



469

00:45:31,300 --> 00:45:39,670

Now I'm going to hit enter and if we do ps-ef grep Redis.



470

00:45:39,730 --> 00:45:47,750

We can see we have only Redis Sentinel running but there is no Redis Server running.



471

00:45:48,120 --> 00:45:56,470

So Redis Server is down . Okay let's clear the screen and let's wait for around 20 more seconds.



472

00:45:57,560 --> 00:46:03,650

Because our setting is set to 30 seconds.  So Sentinel is going to take 30 seconds to make sure



473

00:46:03,650 --> 00:46:08,500

that it is down. As we can see now Sentinel is into action.



474

00:46:08,540 --> 00:46:13,040

It has displayed so many logs.



475

00:46:13,050 --> 00:46:17,080

So basically what it is doing here is, if you try to understand the Log.



476

00:46:27,590 --> 00:46:30,720

So yeah, from here actually we can see that it is saying that



477

00:46:34,570 --> 00:46:35,710

+sdown.



478

00:46:35,710 --> 00:46:39,850

So basically what that means is you can see here +sdown.



479

00:46:39,850 --> 00:46:45,670

So basically it has detected that Master is down and it is now trying the failover. You can see the



480

00:46:45,670 --> 00:46:50,740

logs here and then it is trying the action, which is called Vote for Leader.



481

00:46:50,860 --> 00:46:51,120

Okay.



482

00:46:51,130 --> 00:47:00,540

So this is where you know, a minimum of 2 Sentinel nodes has to Vote and Agree and choose a, you know,



483

00:47:00,620 --> 00:47:02,350

Node which can become Master.



484

00:47:02,670 --> 00:47:02,960

Okay.



485

00:47:02,980 --> 00:47:07,030

So here you can see they have said Elected leader master, which is



486

00:47:09,820 --> 00:47:19,220

currently it is pointing to this Master Node and now if you see here, we can see here it has promoted



487

00:47:19,220 --> 00:47:24,040

one of the Slave Node, which is 10.128.0.4  as the Master Node.



488

00:47:44,570 --> 00:47:48,560

and also if you see at the bottom, now you can see,



489

00:47:52,630 --> 00:47:59,210

if you look at here.  You can see that IP address, 10.128.0.5  is still a Slave.



490

00:47:59,530 --> 00:48:07,870

And also  the previous master node which was running on 10.128.0.2  has now turn into a Slave



491

00:48:07,870 --> 00:48:08,110

Node.



492

00:48:10,960 --> 00:48:12,130

OK.



493

00:48:12,360 --> 00:48:20,640

Now we can actually log into Node 4 which is 10.128.0.4,  which has become Master Node.



494

00:48:30,200 --> 00:48:37,130

Okay and let's perform a Set operation to make sure that we are able to write something because Master,



495

00:48:37,460 --> 00:48:41,860

on Master node we should be able to do the write operations.



496

00:48:41,860 --> 00:48:48,330

Okay so I'm going to enter a Product Value or a Product Name in this case.



497

00:48:49,030 --> 00:48:49,290

Okay.



498

00:48:49,300 --> 00:48:56,070

So once I hit enter, you can see it is, if I make it a bit bigger you can see it has replied with.



499

00:48:56,110 --> 00:48:57,200

Okay.



500

00:48:57,370 --> 00:49:00,580

Which means it is now accepting our write request.



501

00:49:02,610 --> 00:49:11,010

So I will exit from here and what we will do is, let's start Redis Server again and see what happens



502

00:49:11,010 --> 00:49:12,560

when Redis Server is started or



503

00:49:12,570 --> 00:49:14,550

What is the action  which Sentinel is going to take.



504

00:49:18,340 --> 00:49:23,140

Right now if you see there is still a Line which is saying +sdown.  So +sdown means is, one



505

00:49:23,140 --> 00:49:28,910

of the Slave is down and this is the IP address of the Slave, which is down. Okay.



506

00:49:28,950 --> 00:49:36,250

So it should be changing to -s down.  Once we bring up the server again okay.



507

00:49:36,280 --> 00:49:42,720

So once we bring up the previous Master up again. It is not going to be promoted to Master.



508

00:49:42,810 --> 00:49:44,370

You know it is still going to be a Slave.



509

00:49:46,140 --> 00:49:54,570

So this will continue to work as a slave as long as you know, none of the node goes down.  So this



510

00:49:54,570 --> 00:50:01,570

node which is running on, 10.128.0.4  will continue to work as a Master.



511

00:50:01,680 --> 00:50:06,850

Okay so let's start Redisdb on



512

00:50:06,860 --> 00:50:07,750

Master node again.



513

00:50:07,760 --> 00:50:08,990

I mean Previous Master Node.



514

00:50:18,450 --> 00:50:24,980

Okay hit enter and now you can see, as soon as we hit enter, services  started here.



515

00:50:24,990 --> 00:50:32,010

There is a new entry came which is saying -sdown Slave. So means now it has detected that Slave



516

00:50:32,010 --> 00:50:33,220

node is up again.



517

00:50:33,300 --> 00:50:33,500

Okay.



518

00:50:33,510 --> 00:50:41,270

This is the same Slave Node which was previously  Master. So this also verifies that our Master or our



519

00:50:41,270 --> 00:50:46,880

Cluster is working fine, because Master Slaves are able to connect to each other,  able to reply to each



520

00:50:46,880 --> 00:50:47,140

other.



521

00:50:50,010 --> 00:50:58,470

Let's also see the value you know, which we have inserted in, by connecting to new master node is replicated



522

00:50:58,500 --> 00:51:02,160

now to this Slave Node, which  was down and now it has come up.



523

00:51:02,280 --> 00:51:02,570

Okay.



524

00:51:02,580 --> 00:51:03,280

So let's see



525

00:51:08,810 --> 00:51:09,330

one second.



526

00:51:09,330 --> 00:51:11,300

So yeah let me clear the screen first.



527

00:51:14,420 --> 00:51:20,360

So I will use Redis-cli using -h,  we will specify the Host which we want to



528

00:51:20,360 --> 00:51:20,870

connect to.



529

00:51:20,890 --> 00:51:25,220

So we want to connect to 10.128.0.4,  which is the New Master.



530

00:51:26,490 --> 00:51:32,780

Oh I'm sorry, this case we should be connecting to 10.128.0.2, which is the Slave Node which has



531

00:51:32,780 --> 00:51:33,650

just started now.



532

00:51:34,640 --> 00:51:35,120

Okay.



533

00:51:35,180 --> 00:51:44,710

And Port is going to be 6 3 7 9 and if we do Get product.  Now we can see that we have got the product



534

00:51:44,710 --> 00:51:52,930

value. So this node was previously a master node.  It went down, then Sentinel made,  one of the existing



535

00:51:52,930 --> 00:51:57,880

Slave Node, a master node which is 10.128.0.4



536

00:51:58,030 --> 00:52:04,660

And then we brought this node back again and this node is now going to continue to act as Slave Node.



537

00:52:07,210 --> 00:52:07,460

okay.



538

00:52:07,480 --> 00:52:14,270

So that's all about setting up Cluster in a Production Environment and making your Redis in a,



539

00:52:15,140 --> 00:52:16,960

I mean  running in a High Availability Mode.