AWS Cost Saving Tip 8: Use Amazon S3 Reduced Redundancy Storage

Amazon S3 is one of the widely popular and durable Object Storage service. AWS S3 team applies many innovative techniques to provide and maintain this level of durability and redundancy to end customers.  At the same time they are very efficient in providing high durability at low cost as well.They clearly understand in real world, not all the Objects (files/documents etc) have same usage lifecycle-> some of them have limited life time and some can be reconstructed from the original file. In this context, high durability might be an expensive proposition to store temporary and reproducible files. Such customers may prefer some relaxation in storage durability in exchange for a reduced price from the cloud provider like AWS.  

Amazon S3 introduced RRS option to customers keeping this requirement in mind. Reduced Redundancy Storage (RRS) is a storage option within Amazon S3 that enables customers to reduce their costs by storing non-critical, reproducible data at lower levels of redundancy than Amazon S3’s standard storage.

“It provides a cost-effective, highly available solution for distributing or sharing content that is durably stored elsewhere, or for storing thumbnails, transcoded media, or other processed data that can be easily reproduced. “ - AWS

Some of the Do/Don’ts you should know while using RRS options are:

• If you’re storing media content on-premise but you need to provide accessibility to your customers, channel partners, or employees in AWS Cloud -> RRS is a low-cost solution for storing and sharing this content efficiently from AWS Cloud. Have a VPN tunnel or AWS Direct Connect configured between On-premise DC and Amazon VPC Cloud. Reconstruct the file from the original content and store it cost effectively in Amazon S3 RRS.
• “Whether you’re storing pharmaceutical data for analysis, or financial data for computation and pricing, Amazon S3 is an ideal location to store your original content. You can then send this content to Amazon EC2 for computation, resizing, or other large scale analytics – without incurring any data transfer charges for moving the data between the services. You can then choose to store the resulting, reproducible content using Amazon S3’s Reduced Redundancy Storage feature”. - AWS
• If you are a photo site like SmugMug, Flickr or Stock photography site like IPNStock, you can store the reproducible thumbnails in S3 RRS and original photos in S3 Standard option.
• Imagine you have series of background jobs running in your workflow and some of them create intermediate temporary files in the process.  Since the intermediate files can be recreated they become good candidates for RRS storage.
• If you are storing hourly backups of your database, then RRS is not a good option for them and it is advised to store them in Amazon S3 Standard itself

Exploring Amazon S3 RRS option in detail:

Amazon S3’s standard and reduced redundancy options both store data in multiple facilities and on multiple devices, but with RRS the cost is less because the RRS option stores objects on multiple devices across multiple facilities, providing 400 times the durability of a typical disk drive, but does not replicate objects as many times as standard Amazon S3 storage, and thus is even more cost effective than standard S3.

In terms of durability, Amazon S3 standard storage is architected to provide 99.999999999% durability and to sustain the concurrent loss of data in two facilities, RRS is architected to provide 99.99% durability to sustain the loss of data in a single facility. RRS is also backed with the Amazon S3 Service Level Agreement, providing financial penalties if availability is less than 99.9% in a given month.  For example, if you store 10,000 objects in Amazon S3 using the RRS option, you can on average expect to incur an annual loss of a single object (i.e. 0.01% of 10,000 objects). This annual loss represents an expected average and does not guarantee the loss of 0.01% of objects in a given year. In case an RRS object has been lost, Amazon S3 will return a 405 error on requests made to that object. Amazon S3 also offers notifications for Reduced Redundancy Storage (RRS) object loss. Customers can configure their bucket so that when Amazon S3 detects the loss of an RRS object, a notification will be sent through Amazon Simple Notification Service (SNS). This enables customers to replace lost RRS objects whenever needed. 

When you use Amazon S3 Standard or RRS option, there is no difference in latency, throughput etc and you can secure or archive to glacier the same way you do it on regular S3 standard storage.

Standard vs RRS Cost saving analysis:

Imagine a stock photography site having a collection of 98,000,000 original images. These images have to be converted to variety of sizes like Thumbnails & Small sized images for rendering and other bigger sizes for purchasing. The rendering images are typically shown in search and detail screens of the stock photography website. They are reproducible from original images and are very good candidates for Amazon S3 RRS option. Imagine the thumbnails are ~10 KB in size and Small images are ~50KB in size now let us explore how we can use Amazon S3 RRS option in this case and save costs:

Region: US-East 

Storage Size	Standard	Reduced Redundancy
First 1 TB / month	$0.095 per GB	$0.076 per GB
Next 49 TB / month	$0.080 per GB	$0.064 per GB

Standard vs RRS Savings Matrix:

98,000,000 images translates to ~935 GB of thumbs and ~4673 GB of small size images. The below matrix provides a cost comparison between storing these images in Std vs RRS option:

Image Size	Size (GB)	Standard ($)	RRS ($)	Savings (%)
Thumbs	935	88	71	20
Small	4673	389	311	20

Savings: From the above case you can conclude that by using RRS option you can save around 20% in your storage costs compared to Amazon S3 standard option.  

Other Tips

Cost Saving Tip 1: Amazon SQS Long Polling and Batch requests
Cost Saving Tip 2: How right search technology choice saves cost in AWS ?
Cost Saving Tip 3: Using Amazon CloudFront Price Class to minimize costs
Cost Saving Tip 4 : Right Sizing Amazon ElastiCache Cluster
Cost Saving Tip 5: How Amazon Auto Scaling can save costs ?
Cost Saving Tip 6: Amazon Auto Scaling Termination policy and savings
Cost Saving Tip 7: Use Amazon S3 Object Expiration
Cost Saving Tip 8: Use Amazon S3 Reduced Redundancy Storage