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Things to Remember


Advanced High Availability
Setting the Scene
43m 44s
Start course
3h 31m

Course Description

In this course, you'll gain a solid understanding of the key concepts for Domains One and Seven of the AWS Solutions Architect Professional certification: High Availability, Scalability and Business Continuity. 

Course Objectives

By the end of this course, you'll have the tools and knowledge you need to successfully accomplish the following requirements for this domain, including:

  • Demonstrate ability to architect the appropriate level of availability based on stakeholder requirements.
  • Demonstrate ability to implement DR for systems based on RPO and RTO.
  • Determine appropriate use of multi-Availability Zones vs. multi-Region architectures.
  • Demonstrate ability to implement self-healing capabilities.
  • Demonstrate ability to implement the most appropriate data storage scaling architecture
  • High Availability vs. Fault Tolerance.
  • Scalability and Elasticity.

Intended Audience

This course is intended for students seeking to acquire the AWS Solutions Architect Professional certification. It is necessary to have acquired the Associate level of this certification. You should also have at least two years of real-world experience developing AWS architectures. 


As stated previously, you will need to have completed the AWS Solutions Architect Associate certification, and we recommend reviewing the relevant learning path in order to be well-prepared for the material in this one. 

This Course Includes

  • 1 hour and 13 minutes of high-definition video.
  • Expert-led instruction and exploration of important concepts. 
  • Coverage of critical concepts for Domain one and Domain Seven of the AWS Solutions Architect - Professional certification exam. 

What You Will Learn

  1. Designing a back-up and recovery solution.
  2. Implementing DR based on RTO/ RPO.
  3. RDS back up and restore and self healing capabilities.
  4. Points to remember for the exam.

A few points to keep in mind about EBS Snapshots. If you make periodic snapshots of a volume, the snapshots are incremental. So that only the blocks on the device that have changed after your last snapshot are saved to the new snapshot. "Snapshots occur asynchronously." The point in time snapshot is created immediately but the status of the snapshot is pending until the snapshot is complete, which can take several hours for large, initial snapshots or subsequent snapshots where many blocks might have changed. There's a limit of five pending snapshots for a single volume. If you receive a "ConcurrentSnapshotLimitExceeded" error or have a question about it while trying to create multiple, concurrent snapshots of the same volume, wait for one or more of the pending snapshots to complete before creating another snapshot on that volume. Although you can take a snapshot of a volume while a previous snapshot of that volume is in the pending status, having multiple pending snapshots of a volume may result in reduced performance until the snapshot's complete. "Snapshots that are taken from an encrypted volumes are automatically encrypted." And volumes that are created from encrypted snapshots are also automatically encrypted. The data in your encrypted volumes and any associated snapshots is protected both at rest and in motion. By default, only you can create volumes from snapshots that you own. However, you can share your unencrypted snapshots with specific AWS accounts. For others to use your shared encrypted snapshot, you must also share your CMK key that was used to encrypt the volume. Another option for sharing is to copy the contents to a non encrypted volume and make a snapshot of that unencrypted volume and share that. You can take a snapshot of an attached volume that's in use. However snapshots only capture data that has been written to your Amazon EBS volume at the time the snapshot command is issued. Now this might exclude data that has been cached by any applications or even by the operating system. So our best practice is to pause any file writes to the volume long enough to take that snapshot. Now if you can't pause all file writes to the volume, you should unmount the volume from within the instance, issue the snapshot command, and then remount the volume to ensure a consistent and complete snapshot. You can remount and use our volume while the snapshot status is pending. To create a snapshot for Amazon EBS volumes that service root devices, you should stop the instance before taking the snapshot. The storage gateway, you can create storage volumes of up to 32 terabytes in size and attach them as iSCSI devices from your on premise application servers. Do remember though that the three types of storages are quite different. The AWS Storage Gateway requires an application or VM that you need to install on your network or data center. And then you can configure that from the AWS console. Now if users need to access back up or archive data during back up or recovery use gateway cached storage gateway. Gateway cached volumes let you use Amazon's Simple Storage Service as your primary data store while retaining frequently accessed data locally in your storage gateway. Remember you need those two discs, you need a cached volume and you need a gateway volume. In the gateway cached volume solution, AWS storage gateway stores all your on premise application data in a storage volume in S3. Gateway cached volumes can range from one gigabyte to 32 terabytes in size, and it must be rounded to the nearest gigabyte. Each gateway can configured for gateway cached volumes can support up to 32 volumes for a total maximum storage volume of one terabyte or one, 1000 terabytes or one petabyte. Gateway storage requires setting up a local disk to use as your cache disk, remember that. So the gateway VTL exposes several tape drives and a virtual media changer which are referred to collectively as VTL devices. And those are iSCSI targets. You can only connect one application to each iSCSI target when you're using the virtual gateway VTL.

About the Author
Andrew Larkin
Head of Content
Learning Paths

Head of Content

Andrew is an AWS certified professional who is passionate about helping others learn how to use and gain benefit from AWS technologies. Andrew has worked for AWS and for AWS technology partners Ooyala and Adobe.  His favorite Amazon leadership principle is "Customer Obsession" as everything AWS starts with the customer. Passions around work are cycling and surfing, and having a laugh about the lessons learnt trying to launch two daughters and a few start ups.