Resilience of Storage Services on AWS
Tags: aws, architecture, cloud, resilience
Published: 2022-05-12 05:18:59

AWS has the most reliable Global Infrastructure for cloud that allows you to build secure, scalable and highly available workloads in the cloud. While building solutions on AWS, it is important to know the data resiliency offered by AWS cloud. 

In this post I will talk about the resiliency of storage services on AWS. We will look at the following AWS storage services:
- Instance Store
- Amazon Elastic Block Store (Amazon EBS)
- Amazon Elastic File System (Amazon EFS)
- Amazon FSx for Windows
- Amazon FSx for Lustre
- Amazon Simple Storage Service (Amazon S3)
- AWS Storage Gateway

**Instance Store**	

Instance stores provides temporary block-level storage for EC2 instances. 

> Instance Stores do not offer any level of resiliency.

The data in an instance store persists only during the lifetime of its associated instance. The data in the instance store is lost if the instance stops, hibernates, terminates or the underlying disk drive fails. However, data in the instance store is persisted in case of instance reboot.

**Amazon Elastic Block Store (Amazon EBS)**	

Amazon EBS provides block-level persistent storage volumes attached to EC2 instances. 

> EBS volumes are replicated within an Availability Zone (AZ). 

Amazon EBS volumes are designed to be highly available, reliable, and durable. Amazon EBS volume data is replicated across multiple servers in an Availability Zone to prevent the loss of data from the failure of any single component.

Amazon EBS also has snapshot feature to help support your data resiliency and backup needs.


**Amazon Elastic File System (Amazon EFS)**	

Amazon EFS provides a simple, serverless, set-and-forget elastic file system. 

> Amazon EFS file systems (except for EFS One Zone) are resilient to one or more Availability Zone failures within an AWS Region.

With EFS Standard storage classes, every EFS file system object (such as directory, file, and link) is redundantly stored across multiple Availability Zones. You can architect your application to failover from one AZ to other AZs in the Region to ensure the highest level of application availability. 

With EFS One Zone storage classes, your data is redundantly stored within a single Availability Zone. 

Mount targets are designed to be highly available within an AZ for all EFS storage classes.

Amazon EFS is designed to sustain concurrent device failures by quickly detecting and repairing any lost redundancy. 

Amazon EFS also supports resiliency needs using features such as EFS Replication and data backup using AWS Backup or EFS-to-EFS backup. 

**Amazon FSx for Windows**	

Amazon FSx for Windows provides fully managed file storage built on Windows Server.

> Single-AZ file systems designed to be resilient within an Availability Zone by replicating data within single AZ. Multi-AZ file systems provide redundancy across multiple AZs.

Amazon FSx automatically replicates your data within an Availability Zone to protect it from component failure and automatically replaces infrastructure components in the event of a failure. 

Amazon FSx offers Multi-AZ option that include an active and standby file server in separate AZs. In the event of a failure of the active file server or an AZ, Amazon FSx automatically fails over to the standby so you can resume file system operations without a loss of availability to your data.

Amazon FSx also automatically takes highly durable, file-system consistent daily backups to S3 (using Volume Shadow Copy Service), and allows you to take additional backups at any point.

**Amazon FSx for Lustre**	

Amazon FSx for Lustre provides fully managed shared storage with the scalability and performance of the popular Lustre file system.

> Data replicated within an Availability Zone with Persistent file system.

Amazon FSx for Lustre provides a parallel file system, where data is stored across multiple network file servers to maximize performance and reduce bottlenecks. 

Amazon FSx for Lustre offers a choice of scratch and persistent file systems to accommodate different data processing needs. 

Persistent file systems are ideal for longer-term storage and throughput-focused workloads. In persistent file systems, data is replicated within an AZ, and file servers are replaced automatically if they fail. 

Scratch file systems are ideal for temporary storage and shorter-term processing of data. Data is not replicated and does not persist if a file server fails. 

**Amazon Simple Storage Service (Amazon S3)**	

Amazon S3 is an object storage service built to store and retrieve any amount of data from anywhere.

> S3 objects (except for S3 One Zone-IA) are resilient to three or more Availability Zones in an AWS Region.

S3 Standard, S3 Standard-IA, S3 Intelligent-Tiering, S3 Glacier Instant Retrieval, S3 Glacier Flexible Retrieval, and S3 Glacier Deep Archive storage - these storage classes redundantly store objects on multiple devices spanning a minimum of three Availability Zones in an AWS Region. 

The S3 One Zone-IA storage class stores data redundantly across multiple devices within a single Availability Zone. 

Amazon S3 service is designed to sustain concurrent device failures by quickly detecting and repairing any lost redundancy, and it also regularly verifies the integrity of your data using checksums.

Amazon S3 offers several other features to help support your data resiliency and backup needs such as lifecycle configuration, versioning, object locking and replication.


**AWS Storage Gateway**	

AWS Storage Gateway is a hybrid cloud storage service that provide on-premises applications with access to virtually unlimited cloud storage.

> AWS Storage Gateway provides High Availability on VMware.

Storage Gateway achieves high availability on VMware through a series of continuous health-checks against critical operations of the gateway that is integrated with VMware vSphere High Availability (VMware HA). With this integration, Storage Gateway automatically recovers from most service interruptions in under 60 seconds (whether deployed in an on-premises VMware environment, or in VMware Cloud on AWS). This protects storage workloads against hardware, hypervisor, or network failures, storage errors, as well as software issues that lead to connection timeouts or file-share, volume, or tape unavailability.

Storage Gateway also supports your data resiliency and backup needs using features such as volume backup, volume cloning, and tape archival.

**Conclusion**
I hope this post helps you understand how your data is reliably stored on AWS using the built-in resiliency offered by various AWS Storage Services.