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  5. A Practical Understanding of Alibaba Cloud RDS

Features of RDS

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This course explores Alibaba's RDS service looking at RDS instances, features, security, and the foundational concepts of the service. You'll follow along with guided demos from the Alibaba Cloud platform that will show you how to use and manage the RDS service.

Learning Objectives

  • Get a foundational understanding of the RDS service
  • Create an RDS instance
  • Set up backups and temporary instances
  • Set up read-only instances
  • Use monitoring, metrics, and alerts in RDS
  • Upgrading RDS Instance Configuration

Intended Audience

This course is intended for anyone who wants to learn more about Alibaba RDS, as well as anyone studying for the ACP Cloud Computing certification exam.


To get the most out of this course, you should have a basic understanding of the Alibaba Cloud platform.


Let's now look at some of RDS's key features. We'll start with backup. So RDS offers automatic backup, meaning you can create a backup policy and adjust the timing of RDS data and log backups. You can see an example of that on the right. In the backup cycle configuration for an RDS instance, you can say how long the backup should be retained, how often they should be made, and at what time of day, and you can enable or disable log backup. So you can retain logs in addition to the actual database data itself.

Automatic backup currently supports physical backup. We also offer manual backups, which allow you to make a backup of your RDS data at any time. Manual backup supports both physical and logical backup. In terms of cost, we have a formula for calculating how much database backup space to give you, and below a certain threshold, backups are free. So if you've purchased an RDS instance that has 20 gigabytes of space allocated to it, you can make up to 10 gigabytes of backups for free. If you have a 100 gigabyte RDS instance, you can make up to 50 gigabytes worth of backup for free. So keep that in mind.

Once you exceed that threshold, which is one half the size of your purchased storage capacity, then we do start charging you for backups. Also, you can obtain a link, a temporary link to any of your manual or automatic backups as needed so this way you can download an offline copy of your instance's backup file, which you can use for offline analysis or repair or for importing into a different database somewhere else. If you'd like to keep your database backups long-term, but are looking for a cost efficient way to do it, our storage module does support dumping your backup files into OSS, so you can keep them in OSS archive storage, which provides very cost-efficient, offline long-term storage.

Data recovery, I won't go into a lot of detail here. Data recovery is fairly complex. There are many ways to do data recovery for an RDS instance. If you've accidentally deleted a database or table, or if your RDS instance has failed, you can recover from any of your manual or automatic backups. The links in blue here explain different ways that you can achieve that for different backup and restore scenarios. Of course, if you're watching the video, you won't be able to click on the links, but if you search for the terms in blue, if you perform a Google search or a search within our documentation page, you should be able to find these relevant articles. And most of the examples are for MySQL, but of course, backup and restore is supported just as well for our other engines like Microsoft SQL. If you need multi-region disaster recovery, that's also achievable.

So let's say you want to have live or near-real-time failover between Shanghai and Beijing. Of course, the RDS service, just like ECS, is a region service, it's a regional service, meaning that an RDS database can't migrate from one region to another, but can run two RDS instances in two different regions and sync data between them using our DTS or data transmission service as shown here on the slide. So this is an option for high-speed, high-reliability, multi-region failover.

You can run two live databases simultaneously. Let's say one is in Beijing and one is in Shanghai. If the database in Beijing fails, you can failover to Shanghai with little to no data loss and that's made possible because DTS will synchronize data from the Beijing database to the Shanghai database and vice versa. It has a data subscription mode which will track changes to each database and then update the other database with those changes.

Another helpful feature of RDS, which is currently limited to MySQL, is read-only instances. So you can add one or more read-only instances to your RDS MySQL deployment and this can take read pressure off of your primary or master instance. This is great if you have a spike in traffic or your site suddenly increases in popularity and you start having a lot of database read requests come in, the read-only databases can take that pressure off of the primary or master instance. I should point out though that you can't use read-only instances to achieve HA. They're not for high availability. They can not be promoted to a master. If you want to have high availability, you need to purchase the HA version of the RDS service.

Another neat feature of the read-only instances for MySQL is that there's built in read-write splitting. So we provide a database connection endpoint that automatically performs read-write splitting, meaning your application doesn't even have to know that there are read-only instances that can be transparently handled by RDS. RDS storage can also be extended in several different ways. You can add a cache layer. We have managed Memcache and Redis services which you can use to get higher QPS than you can manage with RDS alone. These provide high performance responses to database queries for commonly accessed data. You can also offload large database items, like say a user photographs from an online forum and store them in OSS to take pressure off of your RDS instance. So large items in your database could potentially be moved to another service like OSS.

Next, let's take a look at monitoring and security.

About the Author
Learning Paths

Alibaba Cloud, founded in 2009, is a global leader in cloud computing and artificial intelligence, providing services to thousands of enterprises, developers, and governments organizations in more than 200 countries and regions. Committed to the success of its customers, Alibaba Cloud provides reliable and secure cloud computing and data processing capabilities as a part of its online solutions.