August 2019
Beginner to intermediate
232 pages
3h 50m
Chinese
Content preview from Web容量规划之美
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168
第
6
章
挑战
有效利用云的弹性是非比寻常的。具体来说，必须注意以下事项：
•
大规模的缩容可能会带来延迟和吞吐量降低等不利影响（在最坏的情况下，服
务可能变得不可用）。较高的延迟会降低直接用户的体验。此外，从公司的角
度来看，更低的吞吐量会对系统底限产生负面影响（一般来说，这对于任何最
终用户来说都是服务）。
•
过度扩容会导致过度膨胀，会占用较多的云资源。当然，较高的运营成本会对
容量扩展底限产生不利影响。
图
6-1
说明这些注意事项。此外，跨多个应用程序的云弹性的有效利用可以控制总
体的成本。
图
6
-
1
：服务能力过剩与服务能力不足
从长远来看，按需使用比使用保留的实例要昂贵得多。因此，开发新技术以系统
地利用云的弹性是非常关键的。
注
2
注
2
：
我们鼓励你在
AWS
比较保留价格和需求情况，参见
https://aws.amazon.com/ec2/
pricing/
。
169
自动扩缩容
公共云竞价市场
对于大多数公有云
，
你可以根据预期的实例出价
。
这些实例的价格比需求实例
低
90%
，
因此可以显著降低成本
。
亚马逊
EC2
将这种情况称为竞价实例
。
注
3
竞价实例市场是标准化产品交易立即交付的市场
，
市场上产品的价格取决于供
求关系
。
谷歌计算引擎的虚拟机和
Amazon EC2 Spot
实例的机器数基本相等
。
为简便起见
，
我们在这里只讨论与亚马逊 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.