1
00:00:00,210 --> 00:00:02,020
Okay, so let's do a deep dive

2
00:00:02,020 --> 00:00:04,680
on EC2 spot instances.

3
00:00:04,680 --> 00:00:06,570
We know that with a spot instance,

4
00:00:06,570 --> 00:00:10,870
you can get a discount up to 90% compared to On-Demand.

5
00:00:10,870 --> 00:00:12,420
So that's huge cost saving.

6
00:00:12,420 --> 00:00:13,950
How does that work?

7
00:00:13,950 --> 00:00:17,190
We define a max spot price that we're willing to pay

8
00:00:17,190 --> 00:00:18,440
for that spot instance.

9
00:00:18,440 --> 00:00:23,080
And then as long as the instance is having a spot price

10
00:00:23,080 --> 00:00:25,910
that is less than the max price we're willing to pay,

11
00:00:25,910 --> 00:00:27,810
then we keep that instance.

12
00:00:27,810 --> 00:00:29,520
So that max spot price, I will show it to you

13
00:00:29,520 --> 00:00:30,520
in the next slide.

14
00:00:30,520 --> 00:00:33,880
But the hourly spot will vary based on offer and capacity,

15
00:00:33,880 --> 00:00:35,720
and so it will go up and it will go down.

16
00:00:35,720 --> 00:00:38,500
And if somehow the current spot price

17
00:00:38,500 --> 00:00:40,940
goes over the max price you have defined,

18
00:00:40,940 --> 00:00:42,510
then you have two options.

19
00:00:42,510 --> 00:00:43,910
And for these two options,

20
00:00:43,910 --> 00:00:46,120
you have a two minutes grace period.

21
00:00:46,120 --> 00:00:48,170
So that gives you a little bit of time to do these things.

22
00:00:48,170 --> 00:00:51,550
And the options can be either you're stopping your instance,

23
00:00:51,550 --> 00:00:54,020
that means that you shut down everything you were doing,

24
00:00:54,020 --> 00:00:55,450
then you stop your instance.

25
00:00:55,450 --> 00:00:58,293
And so if one day, the spot price goes below your max price,

26
00:00:58,293 --> 00:01:00,220
then you can restart your instance

27
00:01:00,220 --> 00:01:02,660
and continue where you left it off.

28
00:01:02,660 --> 00:01:05,720
Or if you don't need the state on your EC2 instance,

29
00:01:05,720 --> 00:01:08,400
you can just choose to terminate your instance

30
00:01:08,400 --> 00:01:09,250
and let it go.

31
00:01:09,250 --> 00:01:10,460
And then that would assume

32
00:01:10,460 --> 00:01:12,210
that anytime you would restart your work,

33
00:01:12,210 --> 00:01:15,000
you can start with a fresh new EC2 instance.

34
00:01:15,000 --> 00:01:17,650
So two strategies based on the type of workload you have,

35
00:01:17,650 --> 00:01:20,530
but you have a two minutes grace periods to do so.

36
00:01:20,530 --> 00:01:23,540
The other strategy, if you don't want your spot instance

37
00:01:23,540 --> 00:01:27,140
to be reclaimed by AWS is to use a spot block.

38
00:01:27,140 --> 00:01:30,410
A spot block is when you block a spot instance

39
00:01:30,410 --> 00:01:32,330
for a specified timeframe.

40
00:01:32,330 --> 00:01:35,000
This can be between one to six hours,

41
00:01:35,000 --> 00:01:38,410
and you get that block without any interruption,

42
00:01:38,410 --> 00:01:40,970
at least on paper, because in the documentation,

43
00:01:40,970 --> 00:01:43,540
but it's really rare, in rare situations,

44
00:01:43,540 --> 00:01:45,430
the instance may be reclaimed.

45
00:01:45,430 --> 00:01:47,850
But overall, when you consider a spot block

46
00:01:47,850 --> 00:01:49,880
think that the instance will not be reclaimed,

47
00:01:49,880 --> 00:01:52,290
that's the whole purpose of the spot block.

48
00:01:52,290 --> 00:01:54,510
So when do we use spot instances?

49
00:01:54,510 --> 00:01:56,530
Well, for batch jobs, data analysis,

50
00:01:56,530 --> 00:01:58,200
workloads that are resilient to failures,

51
00:01:58,200 --> 00:01:59,840
and as I said, they're not great

52
00:01:59,840 --> 00:02:02,410
for critical jobs or databases.

53
00:02:02,410 --> 00:02:05,610
Now let's have a look at the spot instance pricing.

54
00:02:05,610 --> 00:02:07,270
So this is a graph that I obtained directly

55
00:02:07,270 --> 00:02:09,250
from the AWS console.

56
00:02:09,250 --> 00:02:11,760
As you can see here, this gives us the price

57
00:02:11,760 --> 00:02:16,676
for a m4.large instance over three months in the spot zone.

58
00:02:16,676 --> 00:02:20,293
As you can see, you have six lines for US-East-1,

59
00:02:21,732 --> 00:02:23,360
the region and you have six availability zones,

60
00:02:23,360 --> 00:02:24,270
so six prices.

61
00:02:24,270 --> 00:02:27,200
So as you can see, the spot price does vary

62
00:02:27,200 --> 00:02:29,550
based on the AZ you're considering.

63
00:02:29,550 --> 00:02:33,660
As we can see, over three months, it has varied quite a bit.

64
00:02:33,660 --> 00:02:35,470
For example, if you look at that yellow line,

65
00:02:35,470 --> 00:02:38,900
it has varied between 0.4 to 0.45,

66
00:02:38,900 --> 00:02:43,720
all the way down to almost 0.35, let's say and so on.

67
00:02:43,720 --> 00:02:47,630
Let's assume that we are defining a user defined max price

68
00:02:47,630 --> 00:02:51,333
to be this black horizontal bar dotted line.

69
00:02:52,340 --> 00:02:56,300
We'd see is that if the yellow line is above

70
00:02:56,300 --> 00:02:59,380
the dotted line, then the current spot price is going

71
00:02:59,380 --> 00:03:02,090
to be more than the max price we have defined.

72
00:03:02,090 --> 00:03:03,770
In this instance, right here,

73
00:03:03,770 --> 00:03:05,640
we're going to lose our spot instance.

74
00:03:05,640 --> 00:03:07,790
So we have to terminate it or stop it.

75
00:03:07,790 --> 00:03:09,500
But if the price goes down,

76
00:03:09,500 --> 00:03:13,080
so if the yellow line goes down our dotted line,

77
00:03:13,080 --> 00:03:15,930
that means that we are willing to pay that price.

78
00:03:15,930 --> 00:03:18,810
We are gaining that spot instance, in this meantime.

79
00:03:18,810 --> 00:03:20,740
This is how we can optimize the cost

80
00:03:20,740 --> 00:03:23,170
of our workload very easily.

81
00:03:23,170 --> 00:03:28,160
As you can see, the On-Demand price is $0.10 per hour,

82
00:03:28,160 --> 00:03:29,350
so that's really, really cheap.

83
00:03:29,350 --> 00:03:32,610
And then the spot instance price is even cheaper.

84
00:03:32,610 --> 00:03:35,430
It's around 0.4, I would say.

85
00:03:35,430 --> 00:03:38,500
It's a 60% saving in that instance,

86
00:03:38,500 --> 00:03:40,990
for the spot instance pricing, so lots of savings.

87
00:03:40,990 --> 00:03:43,000
And obviously, if you were to define

88
00:03:43,000 --> 00:03:44,550
your user defined max price

89
00:03:44,550 --> 00:03:48,560
to be something like $0.05 per hour,

90
00:03:48,560 --> 00:03:51,110
then no in-spot instances will be reclaimed

91
00:03:51,110 --> 00:03:52,030
because you're always willing

92
00:03:52,030 --> 00:03:54,930
to pay more than the actual spot instance price.

93
00:03:54,930 --> 00:03:57,770
So no one can predict how the price goes over time.

94
00:03:57,770 --> 00:03:59,760
But as you can see, it can be rather stable.

95
00:03:59,760 --> 00:04:01,930
It can fluctuate a little bit, but overall,

96
00:04:01,930 --> 00:04:05,373
it still provides you huge savings compared to On-Demand.

97
00:04:06,670 --> 00:04:09,780
Next, how do you terminate a spot instance?

98
00:04:09,780 --> 00:04:13,380
So we have to first understand how a spot request works.

99
00:04:13,380 --> 00:04:15,630
For this, let's consider a spot request.

100
00:04:15,630 --> 00:04:16,920
With a spot request,

101
00:04:16,920 --> 00:04:19,940
you are defining how many instances you want,

102
00:04:19,940 --> 00:04:22,029
your maximum price you're going to pay,

103
00:04:22,029 --> 00:04:24,630
the launch specification, so the AMI and so on,

104
00:04:24,630 --> 00:04:27,280
and when your request is valid from and until,

105
00:04:27,280 --> 00:04:30,180
but it could be infinite, and then the request type.

106
00:04:30,180 --> 00:04:31,370
It's very important to understand

107
00:04:31,370 --> 00:04:32,940
there's two types of requests.

108
00:04:32,940 --> 00:04:35,820
You can do one-time request for spot instances

109
00:04:35,820 --> 00:04:38,930
or a persistent request for post instances.

110
00:04:38,930 --> 00:04:40,950
Let's have a look at the difference.

111
00:04:40,950 --> 00:04:42,710
If it's a one-time request,

112
00:04:42,710 --> 00:04:45,560
as soon as your spot request is fulfilled,

113
00:04:45,560 --> 00:04:47,630
your instances are going to be launched.

114
00:04:47,630 --> 00:04:50,490
And then your spot request will go away

115
00:04:50,490 --> 00:04:52,570
because it was a one-time request type.

116
00:04:52,570 --> 00:04:55,370
So in this case, your spot request is going to go away

117
00:04:55,370 --> 00:04:56,520
and you're fine.

118
00:04:56,520 --> 00:04:58,770
But if it's a persistent request type,

119
00:04:58,770 --> 00:05:02,620
that means that we want this number of instances to be valid

120
00:05:02,620 --> 00:05:06,810
as long as the spot request is valid from to valid until.

121
00:05:06,810 --> 00:05:10,830
That means that if somehow your instances do get stopped,

122
00:05:10,830 --> 00:05:12,980
or interrupted based on the spot price,

123
00:05:12,980 --> 00:05:16,340
then your spot requests will go back into action.

124
00:05:16,340 --> 00:05:18,350
When things can be validated

125
00:05:18,350 --> 00:05:21,220
we'll restart spot instances for you.

126
00:05:21,220 --> 00:05:25,200
So if somehow you stop a spot instance, in persistent mode,

127
00:05:25,200 --> 00:05:27,400
and your spot request is still active,

128
00:05:27,400 --> 00:05:30,090
your spot request automatically will be smart enough

129
00:05:30,090 --> 00:05:32,690
to restart a launch instance for you.

130
00:05:32,690 --> 00:05:35,300
And this is something you can also see in this diagram,

131
00:05:35,300 --> 00:05:36,920
but I won't spend too much time on it.

132
00:05:36,920 --> 00:05:38,230
So what you understand out of it

133
00:05:38,230 --> 00:05:42,600
is that if you want to cancel a spot request,

134
00:05:42,600 --> 00:05:44,670
it needs to be in the open state,

135
00:05:44,670 --> 00:05:46,600
the active state, or the disabled state.

136
00:05:46,600 --> 00:05:48,130
That means that basically, it's not failed,

137
00:05:48,130 --> 00:05:50,030
it's not cancelled or it's not closed.

138
00:05:51,164 --> 00:05:54,130
When you want to cancel a spot request,

139
00:05:54,130 --> 00:05:56,050
so if you take the spot request on the left hand side

140
00:05:56,050 --> 00:06:00,123
and you cancel it, it's not going to terminate any instances

141
00:06:00,123 --> 00:06:01,900
that you have launched from before.

142
00:06:01,900 --> 00:06:04,230
So it is still your responsibility

143
00:06:04,230 --> 00:06:05,980
to terminate these instances

144
00:06:05,980 --> 00:06:09,060
and not the responsibility of AWS.

145
00:06:09,060 --> 00:06:12,220
So as such, if you want to terminate spot instances

146
00:06:12,220 --> 00:06:14,390
for good and not have them relaunched,

147
00:06:14,390 --> 00:06:17,500
you need to first cancel the spot request,

148
00:06:17,500 --> 00:06:21,410
and then you terminate the associated spot instances.

149
00:06:21,410 --> 00:06:25,200
Because if you were to terminate the spot instances first,

150
00:06:25,200 --> 00:06:27,300
remember, it goes back into the spot request

151
00:06:27,300 --> 00:06:29,920
and a spot request says, okay, you wanted six instances,

152
00:06:29,920 --> 00:06:31,580
but I can see you have zero right now,

153
00:06:31,580 --> 00:06:33,960
I'm going to launch six instances for you.

154
00:06:33,960 --> 00:06:36,060
So again, the right order to cancel

155
00:06:36,060 --> 00:06:38,220
and to terminate spot instances is

156
00:06:38,220 --> 00:06:40,510
to first cancel the spot request to make sure

157
00:06:40,510 --> 00:06:44,010
that no new instances will be launched by AWS.

158
00:06:44,010 --> 00:06:47,200
Then you terminate the associated spot instances.

159
00:06:47,200 --> 00:06:48,200
I'm spending a bit of time on this

160
00:06:48,200 --> 00:06:51,290
because this is something that can come up in the exam.

161
00:06:51,290 --> 00:06:53,100
Okay, next spot fleets.

162
00:06:53,100 --> 00:06:55,780
So this is the ultimate way to save money.

163
00:06:55,780 --> 00:06:58,680
Spot fleets is going to be a way to define for you

164
00:06:58,680 --> 00:07:02,990
to get a set of spot instances, and optionally,

165
00:07:02,990 --> 00:07:05,650
On-Demand instances of what's called a fleet.

166
00:07:05,650 --> 00:07:08,380
And the spot fleet will try its best

167
00:07:08,380 --> 00:07:09,940
to meet the target capacity

168
00:07:09,940 --> 00:07:12,090
with the price constraints you defined.

169
00:07:12,090 --> 00:07:15,060
So it will launch from possible launch pools.

170
00:07:15,060 --> 00:07:17,330
It can have different instance types,

171
00:07:17,330 --> 00:07:20,260
different OS and availability zones.

172
00:07:20,260 --> 00:07:22,093
You're going to define multiple launch pools,

173
00:07:22,093 --> 00:07:24,210
a multiple instance size, multiple everything,

174
00:07:24,210 --> 00:07:27,353
and then the fleet will choose the best

175
00:07:27,353 --> 00:07:31,240
and most appropriate launch pool for you.

176
00:07:31,240 --> 00:07:34,490
When your spot fleet either reaches your budget

177
00:07:34,490 --> 00:07:36,470
or reaches the capacity you wanted,

178
00:07:36,470 --> 00:07:39,170
then it will stop launching instances.

179
00:07:39,170 --> 00:07:41,330
And so you define a strategy

180
00:07:41,330 --> 00:07:44,110
to allocate spot instances in your spot fleet.

181
00:07:44,110 --> 00:07:45,350
That's something to remember.

182
00:07:45,350 --> 00:07:47,500
The first one is lowest price,

183
00:07:47,500 --> 00:07:49,350
and that's going to be the most popular one

184
00:07:49,350 --> 00:07:50,570
going into the exam,

185
00:07:50,570 --> 00:07:54,420
which is that the spot fleets will launch instances

186
00:07:54,420 --> 00:07:57,320
from the pool that has the lowest price

187
00:07:57,320 --> 00:08:00,080
and that gives you a lot of cost optimization.

188
00:08:00,080 --> 00:08:02,640
This is a great option if you have a very short workload.

189
00:08:02,640 --> 00:08:05,470
It can also have a diversified way

190
00:08:05,470 --> 00:08:08,266
to launch your spot instances, in which case,

191
00:08:08,266 --> 00:08:11,680
the spot instances will be distributed

192
00:08:11,680 --> 00:08:14,730
across all the pools that you have defined from before,

193
00:08:14,730 --> 00:08:17,170
which is great for availability and long workloads

194
00:08:17,170 --> 00:08:18,910
because if one pool goes away,

195
00:08:18,910 --> 00:08:21,240
then your other pools are still active.

196
00:08:21,240 --> 00:08:23,730
And then finally, you have capacityOptimized

197
00:08:23,730 --> 00:08:26,980
to launch with the optimal capacity based on the number

198
00:08:26,980 --> 00:08:30,400
of instances and choose the right pool for that.

199
00:08:30,400 --> 00:08:32,610
The idea is that spot fleets can be complicated,

200
00:08:32,610 --> 00:08:35,610
but what you have to remember is that using the spot fleet,

201
00:08:35,610 --> 00:08:37,590
you're able to define multiple launch pools,

202
00:08:37,590 --> 00:08:38,570
multiple instance types

203
00:08:38,570 --> 00:08:40,429
until you're just interesting in real power.

204
00:08:40,429 --> 00:08:43,620
And then if you use the lowestPrice discounts,

205
00:08:43,620 --> 00:08:46,170
or the lowest price rate strategy for spot fleets,

206
00:08:46,170 --> 00:08:48,760
then the spot fleets will automatically request

207
00:08:48,760 --> 00:08:52,150
the spot instances with the lowest price for us.

208
00:08:52,150 --> 00:08:55,180
So spot fleet gives us an extra saving

209
00:08:55,180 --> 00:08:57,680
based on spot instances, because it's smart enough

210
00:08:57,680 --> 00:08:59,990
to choose the right spot instance pools

211
00:08:59,990 --> 00:09:03,090
to allow us to get the maximum amount of savings.

212
00:09:03,090 --> 00:09:05,370
This is the benefit of spot fleets.

213
00:09:05,370 --> 00:09:07,410
Again, you need to understand the difference here

214
00:09:07,410 --> 00:09:10,790
of doing a very simple spot instance request

215
00:09:10,790 --> 00:09:12,840
or you know exactly the type of instance you want

216
00:09:12,840 --> 00:09:15,810
and the AZ you want, to using the spot fleet and saying,

217
00:09:15,810 --> 00:09:17,330
okay, you can choose all these instance types

218
00:09:17,330 --> 00:09:19,990
and all these AZ and what I need from you

219
00:09:19,990 --> 00:09:23,270
is to give me the lowest price, for example.

220
00:09:23,270 --> 00:09:25,840
That's hopefully is giving you a lot of insights

221
00:09:25,840 --> 00:09:28,560
into how spot fleets and spot instances are different.

222
00:09:28,560 --> 00:09:29,560
I hope you like this lecture

223
00:09:29,560 --> 00:09:31,510
and I will see you in the next lecture.