Replace master/slave with primary/replica

After further feedback I've not updated the images and just made
alterations to the READMEs for mentions of master-slave to
primary-replica
pull/217/head
Christopher Mills 2018-09-22 06:59:59 +01:00
parent 53c0cf7de8
commit 399b2bd581
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11 changed files with 33 additions and 33 deletions

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@ -333,7 +333,7 @@ class SpendingByCategory(MRJob):
State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design. State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design.
It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Master-Slave Replicas**? What are the alternatives and **Trade-Offs** for each? It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Primary-Replica Replicas**? What are the alternatives and **Trade-Offs** for each?
We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter. We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter.
@ -347,8 +347,8 @@ We'll introduce some components to complete the design and to address scalabilit
* [API server (application layer)](https://github.com/donnemartin/system-design-primer#application-layer) * [API server (application layer)](https://github.com/donnemartin/system-design-primer#application-layer)
* [Cache](https://github.com/donnemartin/system-design-primer#cache) * [Cache](https://github.com/donnemartin/system-design-primer#cache)
* [Relational database management system (RDBMS)](https://github.com/donnemartin/system-design-primer#relational-database-management-system-rdbms) * [Relational database management system (RDBMS)](https://github.com/donnemartin/system-design-primer#relational-database-management-system-rdbms)
* [SQL write master-slave failover](https://github.com/donnemartin/system-design-primer#fail-over) * [SQL write primary-replica failover](https://github.com/donnemartin/system-design-primer#fail-over)
* [Master-slave replication](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [Primary-replica replication](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [Asynchronism](https://github.com/donnemartin/system-design-primer#asynchronism) * [Asynchronism](https://github.com/donnemartin/system-design-primer#asynchronism)
* [Consistency patterns](https://github.com/donnemartin/system-design-primer#consistency-patterns) * [Consistency patterns](https://github.com/donnemartin/system-design-primer#consistency-patterns)
* [Availability patterns](https://github.com/donnemartin/system-design-primer#availability-patterns) * [Availability patterns](https://github.com/donnemartin/system-design-primer#availability-patterns)
@ -375,7 +375,7 @@ We might only want to store a month of `transactions` data in the database, whil
To address the 200 *average* read requests per second (higher at peak), traffic for popular content should be handled by the **Memory Cache** instead of the database. The **Memory Cache** is also useful for handling the unevenly distributed traffic and traffic spikes. The **SQL Read Replicas** should be able to handle the cache misses, as long as the replicas are not bogged down with replicating writes. To address the 200 *average* read requests per second (higher at peak), traffic for popular content should be handled by the **Memory Cache** instead of the database. The **Memory Cache** is also useful for handling the unevenly distributed traffic and traffic spikes. The **SQL Read Replicas** should be able to handle the cache misses, as long as the replicas are not bogged down with replicating writes.
2,000 *average* transaction writes per second (higher at peak) might be tough for a single **SQL Write Master-Slave**. We might need to employ additional SQL scaling patterns: 2,000 *average* transaction writes per second (higher at peak) might be tough for a single **SQL Write Primary-Replica**. We might need to employ additional SQL scaling patterns:
* [Federation](https://github.com/donnemartin/system-design-primer#federation) * [Federation](https://github.com/donnemartin/system-design-primer#federation)
* [Sharding](https://github.com/donnemartin/system-design-primer#sharding) * [Sharding](https://github.com/donnemartin/system-design-primer#sharding)

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@ -239,7 +239,7 @@ class HitCounts(MRJob):
说明您将迭代地执行这样的操作1)**Benchmark/Load 测试**2)**Profile** 出瓶颈3)在评估替代方案和权衡时解决瓶颈4)重复前面,可以参考[在 AWS 上设计一个可以支持百万用户的系统](../scaling_aws/README.md)这个用来解决如何迭代地扩展初始设计的例子。 说明您将迭代地执行这样的操作1)**Benchmark/Load 测试**2)**Profile** 出瓶颈3)在评估替代方案和权衡时解决瓶颈4)重复前面,可以参考[在 AWS 上设计一个可以支持百万用户的系统](../scaling_aws/README.md)这个用来解决如何迭代地扩展初始设计的例子。
重要的是讨论在初始设计中可能遇到的瓶颈,以及如何解决每个瓶颈。比如,在多个 **Web 服务器** 上添加 **负载平衡器** 可以解决哪些问题? **CDN** 解决哪些问题?**Master-Slave Replicas** 解决哪些问题? 替代方案是什么和怎么对每一个替代方案进行权衡比较? 重要的是讨论在初始设计中可能遇到的瓶颈,以及如何解决每个瓶颈。比如,在多个 **Web 服务器** 上添加 **负载平衡器** 可以解决哪些问题? **CDN** 解决哪些问题?**Primary-Replica Replicas** 解决哪些问题? 替代方案是什么和怎么对每一个替代方案进行权衡比较?
我们将介绍一些组件来完成设计,并解决可伸缩性问题。内部的负载平衡器并不能减少杂乱。 我们将介绍一些组件来完成设计,并解决可伸缩性问题。内部的负载平衡器并不能减少杂乱。
@ -253,7 +253,7 @@ class HitCounts(MRJob):
* [应用层](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#应用层) * [应用层](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#应用层)
* [缓存](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#缓存) * [缓存](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#缓存)
* [关系型数据库管理系统 (RDBMS)](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#关系型数据库管理系统rdbms) * [关系型数据库管理系统 (RDBMS)](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#关系型数据库管理系统rdbms)
* [SQL write master-slave failover](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#故障切换) * [SQL write primary-replica failover](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#故障切换)
* [主从复制](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#主从复制) * [主从复制](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#主从复制)
* [一致性模式](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#一致性模式) * [一致性模式](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#一致性模式)
* [可用性模式](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#可用性模式) * [可用性模式](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#可用性模式)
@ -264,7 +264,7 @@ class HitCounts(MRJob):
要处理 *平均* 每秒 40 读请求(峰值更高),其中热点内容的流量应该由 **内存缓存** 处理,而不是数据库。**内存缓存** 对于处理分布不均匀的流量和流量峰值也很有用。只要副本没有陷入复制写的泥潭,**SQL Read Replicas** 应该能够处理缓存丢失。 要处理 *平均* 每秒 40 读请求(峰值更高),其中热点内容的流量应该由 **内存缓存** 处理,而不是数据库。**内存缓存** 对于处理分布不均匀的流量和流量峰值也很有用。只要副本没有陷入复制写的泥潭,**SQL Read Replicas** 应该能够处理缓存丢失。
对于单个 **SQL Write Master-Slave***平均* 每秒 4paste 写入 (峰值更高) 应该是可以做到的。否则,我们需要使用额外的 SQL 扩展模式: 对于单个 **SQL Write Primary-Replica***平均* 每秒 4paste 写入 (峰值更高) 应该是可以做到的。否则,我们需要使用额外的 SQL 扩展模式:
* [联合](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#联合) * [联合](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#联合)
* [分片](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#分片) * [分片](https://github.com/donnemartin/system-design-primer/blob/master/README-zh-Hans.md#分片)

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@ -241,7 +241,7 @@ To delete expired pastes, we could just scan the **SQL Database** for all entrie
State you would do this iteratively: 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design. State you would do this iteratively: 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design.
It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Master-Slave Replicas**? What are the alternatives and **Trade-Offs** for each? It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Primary-Replica Replicas**? What are the alternatives and **Trade-Offs** for each?
We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter. We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter.
@ -255,8 +255,8 @@ We'll introduce some components to complete the design and to address scalabilit
* [API server (application layer)](https://github.com/donnemartin/system-design-primer#application-layer) * [API server (application layer)](https://github.com/donnemartin/system-design-primer#application-layer)
* [Cache](https://github.com/donnemartin/system-design-primer#cache) * [Cache](https://github.com/donnemartin/system-design-primer#cache)
* [Relational database management system (RDBMS)](https://github.com/donnemartin/system-design-primer#relational-database-management-system-rdbms) * [Relational database management system (RDBMS)](https://github.com/donnemartin/system-design-primer#relational-database-management-system-rdbms)
* [SQL write master-slave failover](https://github.com/donnemartin/system-design-primer#fail-over) * [SQL write primary-replica failover](https://github.com/donnemartin/system-design-primer#fail-over)
* [Master-slave replication](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [Primary-replica replication](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [Consistency patterns](https://github.com/donnemartin/system-design-primer#consistency-patterns) * [Consistency patterns](https://github.com/donnemartin/system-design-primer#consistency-patterns)
* [Availability patterns](https://github.com/donnemartin/system-design-primer#availability-patterns) * [Availability patterns](https://github.com/donnemartin/system-design-primer#availability-patterns)
@ -266,7 +266,7 @@ An **Object Store** such as Amazon S3 can comfortably handle the constraint of 1
To address the 40 *average* read requests per second (higher at peak), traffic for popular content should be handled by the **Memory Cache** instead of the database. The **Memory Cache** is also useful for handling the unevenly distributed traffic and traffic spikes. The **SQL Read Replicas** should be able to handle the cache misses, as long as the replicas are not bogged down with replicating writes. To address the 40 *average* read requests per second (higher at peak), traffic for popular content should be handled by the **Memory Cache** instead of the database. The **Memory Cache** is also useful for handling the unevenly distributed traffic and traffic spikes. The **SQL Read Replicas** should be able to handle the cache misses, as long as the replicas are not bogged down with replicating writes.
4 *average* paste writes per second (with higher at peak) should be do-able for a single **SQL Write Master-Slave**. Otherwise, we'll need to employ additional SQL scaling patterns: 4 *average* paste writes per second (with higher at peak) should be do-able for a single **SQL Write Primary-Replica**. Otherwise, we'll need to employ additional SQL scaling patterns:
* [Federation](https://github.com/donnemartin/system-design-primer#federation) * [Federation](https://github.com/donnemartin/system-design-primer#federation)
* [Sharding](https://github.com/donnemartin/system-design-primer#sharding) * [Sharding](https://github.com/donnemartin/system-design-primer#sharding)

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@ -218,7 +218,7 @@ Refer to [When to update the cache](https://github.com/donnemartin/system-design
State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design. State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design.
It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Master-Slave Replicas**? What are the alternatives and **Trade-Offs** for each? It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Primary-Replica Replicas**? What are the alternatives and **Trade-Offs** for each?
We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter. We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter.
@ -247,7 +247,7 @@ To handle the heavy request load and the large amount of memory needed, we'll sc
### SQL scaling patterns ### SQL scaling patterns
* [Read replicas](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [Read replicas](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [Federation](https://github.com/donnemartin/system-design-primer#federation) * [Federation](https://github.com/donnemartin/system-design-primer#federation)
* [Sharding](https://github.com/donnemartin/system-design-primer#sharding) * [Sharding](https://github.com/donnemartin/system-design-primer#sharding)
* [Denormalization](https://github.com/donnemartin/system-design-primer#denormalization) * [Denormalization](https://github.com/donnemartin/system-design-primer#denormalization)

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@ -245,7 +245,7 @@ For internal communications, we could use [Remote Procedure Calls](https://githu
State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design. State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design.
It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Master-Slave Replicas**? What are the alternatives and **Trade-Offs** for each? It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Primary-Replica Replicas**? What are the alternatives and **Trade-Offs** for each?
We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter. We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter.
@ -259,8 +259,8 @@ We'll introduce some components to complete the design and to address scalabilit
* [API server (application layer)](https://github.com/donnemartin/system-design-primer#application-layer) * [API server (application layer)](https://github.com/donnemartin/system-design-primer#application-layer)
* [Cache](https://github.com/donnemartin/system-design-primer#cache) * [Cache](https://github.com/donnemartin/system-design-primer#cache)
* [Relational database management system (RDBMS)](https://github.com/donnemartin/system-design-primer#relational-database-management-system-rdbms) * [Relational database management system (RDBMS)](https://github.com/donnemartin/system-design-primer#relational-database-management-system-rdbms)
* [SQL write master-slave failover](https://github.com/donnemartin/system-design-primer#fail-over) * [SQL write primary-replica failover](https://github.com/donnemartin/system-design-primer#fail-over)
* [Master-slave replication](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [Primary-replica replication](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [Consistency patterns](https://github.com/donnemartin/system-design-primer#consistency-patterns) * [Consistency patterns](https://github.com/donnemartin/system-design-primer#consistency-patterns)
* [Availability patterns](https://github.com/donnemartin/system-design-primer#availability-patterns) * [Availability patterns](https://github.com/donnemartin/system-design-primer#availability-patterns)
@ -270,7 +270,7 @@ We might only want to store a limited time period of data in the database, while
To address the 40,000 *average* read requests per second (higher at peak), traffic for popular content (and their sales rank) should be handled by the **Memory Cache** instead of the database. The **Memory Cache** is also useful for handling the unevenly distributed traffic and traffic spikes. With the large volume of reads, the **SQL Read Replicas** might not be able to handle the cache misses. We'll probably need to employ additional SQL scaling patterns. To address the 40,000 *average* read requests per second (higher at peak), traffic for popular content (and their sales rank) should be handled by the **Memory Cache** instead of the database. The **Memory Cache** is also useful for handling the unevenly distributed traffic and traffic spikes. With the large volume of reads, the **SQL Read Replicas** might not be able to handle the cache misses. We'll probably need to employ additional SQL scaling patterns.
400 *average* writes per second (higher at peak) might be tough for a single **SQL Write Master-Slave**, also pointing to a need for additional scaling techniques. 400 *average* writes per second (higher at peak) might be tough for a single **SQL Write Primary-Replica**, also pointing to a need for additional scaling techniques.
SQL scaling patterns include: SQL scaling patterns include:

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@ -207,7 +207,7 @@
* 如果你正在配置自己的 **负载均衡器**, 在多个可用区域中设置多台服务器用于 [双活](https://github.com/donnemartin/system-design-primer#active-active) 或 [主被](https://github.com/donnemartin/system-design-primer#active-passive) 将提高可用性 * 如果你正在配置自己的 **负载均衡器**, 在多个可用区域中设置多台服务器用于 [双活](https://github.com/donnemartin/system-design-primer#active-active) 或 [主被](https://github.com/donnemartin/system-design-primer#active-passive) 将提高可用性
* 终止在 **负载平衡器** 上的SSL以减少后端服务器上的计算负载并简化证书管理 * 终止在 **负载平衡器** 上的SSL以减少后端服务器上的计算负载并简化证书管理
* 在多个可用区域中使用多台 **Web服务器** * 在多个可用区域中使用多台 **Web服务器**
* 在多个可用区域的 [**主-从 故障转移**](https://github.com/donnemartin/system-design-primer#master-slave-replication) 模式中使用多个 **MySQL** 实例来改进冗余 * 在多个可用区域的 [**主-从 故障转移**](https://github.com/donnemartin/system-design-primer#primary-replica-replication) 模式中使用多个 **MySQL** 实例来改进冗余
* 分离 **Web 服务器** 和 [**应用服务器**](https://github.com/donnemartin/system-design-primer#application-layer) * 分离 **Web 服务器** 和 [**应用服务器**](https://github.com/donnemartin/system-design-primer#application-layer)
* 独立扩展和配置每一层 * 独立扩展和配置每一层
* **Web 服务器** 可以作为 [**反向代理**](https://github.com/donnemartin/system-design-primer#reverse-proxy-web-server) * **Web 服务器** 可以作为 [**反向代理**](https://github.com/donnemartin/system-design-primer#reverse-proxy-web-server)
@ -238,7 +238,7 @@
* 来自 **Web 服务器** 的会话数据 * 来自 **Web 服务器** 的会话数据
* **Web 服务器** 变成无状态的, 允许 **自动伸缩** * **Web 服务器** 变成无状态的, 允许 **自动伸缩**
* 从内存中读取 1 MB 内存需要大约 250 微秒而从SSD中读取时间要长 4 倍,从磁盘读取的时间要长 80 倍。<sup><a href=https://github.com/donnemartin/system-design-primer#latency-numbers-every-programmer-should-know>1</a></sup> * 从内存中读取 1 MB 内存需要大约 250 微秒而从SSD中读取时间要长 4 倍,从磁盘读取的时间要长 80 倍。<sup><a href=https://github.com/donnemartin/system-design-primer#latency-numbers-every-programmer-should-know>1</a></sup>
* 添加 [**MySQL 读取副本**](https://github.com/donnemartin/system-design-primer#master-slave-replication) 来减少写主线程的负载 * 添加 [**MySQL 读取副本**](https://github.com/donnemartin/system-design-primer#primary-replica-replication) 来减少写主线程的负载
* 添加更多 **Web 服务器** and **应用服务器** 来提高响应 * 添加更多 **Web 服务器** and **应用服务器** 来提高响应
**折中方案, 可选方案, 和其他细节:** **折中方案, 可选方案, 和其他细节:**
@ -344,7 +344,7 @@ SQL 扩展模型包括:
### SQL 扩展模式 ### SQL 扩展模式
* [读取副本](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [读取副本](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [集合](https://github.com/donnemartin/system-design-primer#federation) * [集合](https://github.com/donnemartin/system-design-primer#federation)
* [分区](https://github.com/donnemartin/system-design-primer#sharding) * [分区](https://github.com/donnemartin/system-design-primer#sharding)
* [反规范化](https://github.com/donnemartin/system-design-primer#denormalization) * [反规范化](https://github.com/donnemartin/system-design-primer#denormalization)

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@ -207,7 +207,7 @@ Our **Benchmarks/Load Tests** and **Profiling** show that our single **Web Serve
* If you are configuring your own **Load Balancer**, setting up multiple servers in [active-active](https://github.com/donnemartin/system-design-primer#active-active) or [active-passive](https://github.com/donnemartin/system-design-primer#active-passive) in multiple availability zones will improve availability * If you are configuring your own **Load Balancer**, setting up multiple servers in [active-active](https://github.com/donnemartin/system-design-primer#active-active) or [active-passive](https://github.com/donnemartin/system-design-primer#active-passive) in multiple availability zones will improve availability
* Terminate SSL on the **Load Balancer** to reduce computational load on backend servers and to simplify certificate administration * Terminate SSL on the **Load Balancer** to reduce computational load on backend servers and to simplify certificate administration
* Use multiple **Web Servers** spread out over multiple availability zones * Use multiple **Web Servers** spread out over multiple availability zones
* Use multiple **MySQL** instances in [**Master-Slave Failover**](https://github.com/donnemartin/system-design-primer#master-slave-replication) mode across multiple availability zones to improve redundancy * Use multiple **MySQL** instances in [**Primary-Replica Failover**](https://github.com/donnemartin/system-design-primer#primary-replica-replication) mode across multiple availability zones to improve redundancy
* Separate out the **Web Servers** from the [**Application Servers**](https://github.com/donnemartin/system-design-primer#application-layer) * Separate out the **Web Servers** from the [**Application Servers**](https://github.com/donnemartin/system-design-primer#application-layer)
* Scale and configure both layers independently * Scale and configure both layers independently
* **Web Servers** can run as a [**Reverse Proxy**](https://github.com/donnemartin/system-design-primer#reverse-proxy-web-server) * **Web Servers** can run as a [**Reverse Proxy**](https://github.com/donnemartin/system-design-primer#reverse-proxy-web-server)
@ -238,7 +238,7 @@ Our **Benchmarks/Load Tests** and **Profiling** show that we are read-heavy (100
* Session data from the **Web Servers** * Session data from the **Web Servers**
* The **Web Servers** become stateless, allowing for **Autoscaling** * The **Web Servers** become stateless, allowing for **Autoscaling**
* Reading 1 MB sequentially from memory takes about 250 microseconds, while reading from SSD takes 4x and from disk takes 80x longer.<sup><a href=https://github.com/donnemartin/system-design-primer#latency-numbers-every-programmer-should-know>1</a></sup> * Reading 1 MB sequentially from memory takes about 250 microseconds, while reading from SSD takes 4x and from disk takes 80x longer.<sup><a href=https://github.com/donnemartin/system-design-primer#latency-numbers-every-programmer-should-know>1</a></sup>
* Add [**MySQL Read Replicas**](https://github.com/donnemartin/system-design-primer#master-slave-replication) to reduce load on the write master * Add [**MySQL Read Replicas**](https://github.com/donnemartin/system-design-primer#primary-replica-replication) to reduce load on the write master
* Add more **Web Servers** and **Application Servers** to improve responsiveness * Add more **Web Servers** and **Application Servers** to improve responsiveness
*Trade-offs, alternatives, and additional details:* *Trade-offs, alternatives, and additional details:*
@ -313,7 +313,7 @@ We'll continue to address scaling issues due to the problem's constraints:
* A data warehouse such as Redshift can comfortably handle the constraint of 1 TB of new content per month * A data warehouse such as Redshift can comfortably handle the constraint of 1 TB of new content per month
* With 40,000 average read requests per second, read traffic for popular content can be addressed by scaling the **Memory Cache**, which is also useful for handling the unevenly distributed traffic and traffic spikes * With 40,000 average read requests per second, read traffic for popular content can be addressed by scaling the **Memory Cache**, which is also useful for handling the unevenly distributed traffic and traffic spikes
* The **SQL Read Replicas** might have trouble handling the cache misses, we'll probably need to employ additional SQL scaling patterns * The **SQL Read Replicas** might have trouble handling the cache misses, we'll probably need to employ additional SQL scaling patterns
* 400 average writes per second (with presumably significantly higher peaks) might be tough for a single **SQL Write Master-Slave**, also pointing to a need for additional scaling techniques * 400 average writes per second (with presumably significantly higher peaks) might be tough for a single **SQL Write Primary-Replica**, also pointing to a need for additional scaling techniques
SQL scaling patterns include: SQL scaling patterns include:
@ -344,7 +344,7 @@ We can further separate out our [**Application Servers**](https://github.com/don
### SQL scaling patterns ### SQL scaling patterns
* [Read replicas](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [Read replicas](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [Federation](https://github.com/donnemartin/system-design-primer#federation) * [Federation](https://github.com/donnemartin/system-design-primer#federation)
* [Sharding](https://github.com/donnemartin/system-design-primer#sharding) * [Sharding](https://github.com/donnemartin/system-design-primer#sharding)
* [Denormalization](https://github.com/donnemartin/system-design-primer#denormalization) * [Denormalization](https://github.com/donnemartin/system-design-primer#denormalization)

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@ -289,7 +289,7 @@ $ curl https://social.com/api/v1/friend_search?person_id=1234
### SQL 扩展模式 ### SQL 扩展模式
* [读取副本](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [读取副本](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [集合](https://github.com/donnemartin/system-design-primer#federation) * [集合](https://github.com/donnemartin/system-design-primer#federation)
* [分区](https://github.com/donnemartin/system-design-primer#sharding) * [分区](https://github.com/donnemartin/system-design-primer#sharding)
* [反规范化](https://github.com/donnemartin/system-design-primer#denormalization) * [反规范化](https://github.com/donnemartin/system-design-primer#denormalization)

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@ -256,7 +256,7 @@ For internal communications, we could use [Remote Procedure Calls](https://githu
State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design. State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design.
It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Master-Slave Replicas**? What are the alternatives and **Trade-Offs** for each? It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Primary-Replica Replicas**? What are the alternatives and **Trade-Offs** for each?
We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter. We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter.
@ -290,7 +290,7 @@ Below are further optimizations:
### SQL scaling patterns ### SQL scaling patterns
* [Read replicas](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [Read replicas](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [Federation](https://github.com/donnemartin/system-design-primer#federation) * [Federation](https://github.com/donnemartin/system-design-primer#federation)
* [Sharding](https://github.com/donnemartin/system-design-primer#sharding) * [Sharding](https://github.com/donnemartin/system-design-primer#sharding)
* [Denormalization](https://github.com/donnemartin/system-design-primer#denormalization) * [Denormalization](https://github.com/donnemartin/system-design-primer#denormalization)

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@ -229,7 +229,7 @@ The response would be similar to that of the home timeline, except for tweets ma
State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design. State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design.
It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Master-Slave Replicas**? What are the alternatives and **Trade-Offs** for each? It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Primary-Replica Replicas**? What are the alternatives and **Trade-Offs** for each?
We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter. We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter.
@ -243,8 +243,8 @@ We'll introduce some components to complete the design and to address scalabilit
* [API server (application layer)](https://github.com/donnemartin/system-design-primer#application-layer) * [API server (application layer)](https://github.com/donnemartin/system-design-primer#application-layer)
* [Cache](https://github.com/donnemartin/system-design-primer#cache) * [Cache](https://github.com/donnemartin/system-design-primer#cache)
* [Relational database management system (RDBMS)](https://github.com/donnemartin/system-design-primer#relational-database-management-system-rdbms) * [Relational database management system (RDBMS)](https://github.com/donnemartin/system-design-primer#relational-database-management-system-rdbms)
* [SQL write master-slave failover](https://github.com/donnemartin/system-design-primer#fail-over) * [SQL write primary-replica failover](https://github.com/donnemartin/system-design-primer#fail-over)
* [Master-slave replication](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [Primary-replica replication](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [Consistency patterns](https://github.com/donnemartin/system-design-primer#consistency-patterns) * [Consistency patterns](https://github.com/donnemartin/system-design-primer#consistency-patterns)
* [Availability patterns](https://github.com/donnemartin/system-design-primer#availability-patterns) * [Availability patterns](https://github.com/donnemartin/system-design-primer#availability-patterns)
@ -267,7 +267,7 @@ We'll also want to address the bottleneck with the **SQL Database**.
Although the **Memory Cache** should reduce the load on the database, it is unlikely the **SQL Read Replicas** alone would be enough to handle the cache misses. We'll probably need to employ additional SQL scaling patterns. Although the **Memory Cache** should reduce the load on the database, it is unlikely the **SQL Read Replicas** alone would be enough to handle the cache misses. We'll probably need to employ additional SQL scaling patterns.
The high volume of writes would overwhelm a single **SQL Write Master-Slave**, also pointing to a need for additional scaling techniques. The high volume of writes would overwhelm a single **SQL Write Primary-Replica**, also pointing to a need for additional scaling techniques.
* [Federation](https://github.com/donnemartin/system-design-primer#federation) * [Federation](https://github.com/donnemartin/system-design-primer#federation)
* [Sharding](https://github.com/donnemartin/system-design-primer#sharding) * [Sharding](https://github.com/donnemartin/system-design-primer#sharding)

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@ -262,7 +262,7 @@ For internal communications, we could use [Remote Procedure Calls](https://githu
State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design. State you would 1) **Benchmark/Load Test**, 2) **Profile** for bottlenecks 3) address bottlenecks while evaluating alternatives and trade-offs, and 4) repeat. See [Design a system that scales to millions of users on AWS](../scaling_aws/README.md) as a sample on how to iteratively scale the initial design.
It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Master-Slave Replicas**? What are the alternatives and **Trade-Offs** for each? It's important to discuss what bottlenecks you might encounter with the initial design and how you might address each of them. For example, what issues are addressed by adding a **Load Balancer** with multiple **Web Servers**? **CDN**? **Primary-Replica Replicas**? What are the alternatives and **Trade-Offs** for each?
We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter. We'll introduce some components to complete the design and to address scalability issues. Internal load balancers are not shown to reduce clutter.
@ -294,7 +294,7 @@ Below are a few other optimizations to the **Crawling Service**:
### SQL scaling patterns ### SQL scaling patterns
* [Read replicas](https://github.com/donnemartin/system-design-primer#master-slave-replication) * [Read replicas](https://github.com/donnemartin/system-design-primer#primary-replica-replication)
* [Federation](https://github.com/donnemartin/system-design-primer#federation) * [Federation](https://github.com/donnemartin/system-design-primer#federation)
* [Sharding](https://github.com/donnemartin/system-design-primer#sharding) * [Sharding](https://github.com/donnemartin/system-design-primer#sharding)
* [Denormalization](https://github.com/donnemartin/system-design-primer#denormalization) * [Denormalization](https://github.com/donnemartin/system-design-primer#denormalization)