Cold Storage Comes to Microsoft Cloud

Microsoft has launched a cold storage service on its Azure cloud, offering a low-cost storage alternative for data that’s not accessed frequently.

The launch is a catch-up move by Microsoft, whose biggest public cloud competitors have had cold-storage options for some time. Amazon launched its Glacier service in 2012, and Google rolled out the Cloud Storage Nearline option last year.

The basic concept behind cold storage is that a lot of data people and companies generate is accessed infrequently, so it doesn’t require the same level of availability and access speed as critical applications do. Therefore, the data center infrastructure built to store it can be cheaper than primary cloud infrastructure, with the cost savings passed down to the customer in a cloud provider's case.

Microsoft’s new service is called Cool Blob Storage, and it costs from $0.01 to $0.048 per GB per month, depending on the region and the total volume of data stored. The range for the “Hot” Blob storage tier is $0.0223 to $0.061 per GB, so some customers will be able to cut the cost of storing some of their data in Microsoft's cloud by more than 50 percent if they opt for the "Cool" access tier.

Web-scale data center operators of Microsoft’s caliber have looked at reducing their infrastructure costs by better aligning infrastructure investment with the type of data being stored for some time now. Facebook has revealed more details than others about the way it approaches cold storage, including open sourcing some of its cold storage hardware designs through the Open Compute Project.

Related: Visual Guide to Facebook's Open Source Data Center Hardware

The social network has designed and built separate data centers next to its core sever farms in Oregon and North Carolina specifically for this purpose. The storage systems and the facilities themselves are optimized for cold storage and don’t have redundant electrical infrastructure or backup generators. The design has resulted in significant energy and equipment cost savings, according to Facebook’s infrastructure team.

Read more: Cold Storage: the Facebook Data Centers that Back Up the Backup

Related: Google Says Cold Storage Doesn't Have to Be Cold All the Time

Microsoft hasn’t shared details about the infrastructure behind its new cold storage service. In 2014, however, it published a paper describing a basic building block for an exascale cold storage system called Pelican.

Pelican is a rack-scale storage unit designed specifically for cold storage in the cloud, according to Microsoft. It is a “converged design,” meaning everything, from mechanical systems to hardware and software, was designed to work together.

Pelican’s peak sustainable read rate was 1GB per second per 1PB of storage when the paper came out, and it could store more than 5PB in a single rack, which meant an entire rack’s data could be transferred out in 13 days. Microsoft may have a newer-generation cold storage design with higher throughput and capacity today.

Cool Blob Storage and the regular-access Hot Blob Storage have similar performance in terms of latency and throughput, Sriprasad Bhat, senior program manager for Azure Storage, wrote in a blog post recently announcing the launch.

There is a difference in availability guarantees between the two, however. The Cool access tier offers 99 percent availability, while the Hot access tier guarantees 99.9 percent.

With RA-GRS redundancy option, which replicates data for higher availability, Microsoft will give you a 99.9 percent uptime SLA for Cold access versus 99.99 percent for the Hot access tier.