你有没有在AppEngine中看到DataStore的停机时间？什么是可能性？ [英] Have you expirienced DataStore downtime in AppEngine? What are the odds?

问题描述

Google开始使用高复制数据存储（HRD）作为新应用程序的默认值。

文档中的HR：

HRD是一款高度可用，高度可靠的b $ b可靠存储解决方案。在
计划停机时间内，它仍然可以读写
，并且在面临灾难性
故障时具有极高的
弹性 - 但它的成本高于
主/从选项。

来自文档的M / S：

您的数据可能暂时在数据中心问题期间不可用

或计划停机时间

现在，你有没有经历过停机？如果这个停机免责声明只是一些理论上的问题，并且不会很快发生，我会使用M / S becouse它便宜。

Google处理的数字是多少说宕机？也许他们的宕机时间仅仅是一年的几秒钟，对于某些类型的应用程序来说，这是完全可以接受的。

会爱上来自expirienced AppEngine开发人员的答案。

非常感谢！

解决方案

停机时间不是理论上的 - 它发生在任何分布式系统。有两种类型，粗略来说：本地化和全球化。本地化问题发生在特定机器出现故障而无法提供请求时;全局停机时间发生在整个服务发生时。

两者都可以在App Engine上发生：前者是由于局部硬件故障造成的，后者通常只是由于有计划的维护需要在短时间内将主从数据存储设置为只读。 HR数据存储比MS数据存储处理更强健，并且在维护时段期间不需要只读周期。

一旦新的定价方案生效，这两个数据存储都将以相同的费率收费。

由于这些和其他许多原因，您应该始终在新应用中使用HR数据存储。

Google start to use The High Replication datastore (HRD) as the default for new applications.

HR from the docs:

The HRD is a highly available, highly reliable storage solution. It remains available for reads and writes during planned downtime and is extremely resilient in the face of catastrophic failure—but it costs more than the master/slave option.

M/S from the docs:

your data may be temporarily unavailable during data center issues or planned downtime

Now, have you ever expirienced downtime? If this "downtime disclaimer" is just something theorical and doesn't happen frecuently i would use the M/S becouse it's cheaper.

What are the numbers that Google handle to say "downtime"? maybe their downtime is just a few seconds in a year, something totaly acceptable for some kind of apps.

Would love answers from expirienced AppEngine developers.

Thanks a lot!

解决方案

Downtime isn't theoretical - it happens in any distributed system. There are two types, roughly speaking: localized and global. Localized issues occur when a particular machine has trouble and can't serve requests; global downtime happens when something happens to the service as a whole.

Both can occur on App Engine: the former due to localized hardware failure, and the latter generally only due to planned maintenance that requires setting the master-slave datastore read-only for a brief period. The HR datastore handles both more robustly than the MS datastore, and doesn't require a read-only period during maintenance windows.

Once the new pricing scheme comes into effect, both datastores will be charged at the same rate.

For these and many other reasons, you should always use the HR datastore in new apps.

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