Scott Lowe takes a look at the architecture of an online backup service. How do they offer storage at such competitive prices? Here are some of the building blocks.
Have you ever wondered how some online backup companies can afford to provide the services they provide at what seem to be insanely low prices? One company - Backblaze - has, for quite some time, made their hardware specifications freely available. This has allowed those requiring mass storage to rely on a proven architecture that's used every day to support a profitable business.
Backblaze recently released version 3.0 of their Pod architecture, which sports a whopping 180 TB of capacity in just a few rack units of space and at a cost of less than 6 cents per gigabyte. That 6 cents per gigabyte includes all costs for the storage chassis, 45 x 4 TB hard drives, and all of the components and electronics that make the solution work its magic.
How do they do it? First of all, Backblaze has spent an incredible amount of time testing and validating every part that goes into their Pod architecture. They do so in both lab and real world, mission-critical, customer-facing environments. As such, the company is an authority on specific parts and whether or not parts work or don't work. For example, in Pod 3.0, Backblaze recommends the use of a specific brand of SATA cable. For many, a SATA cable is a SATA cable, but for a company like Backblaze, a faulty SATA cable can be a really bad day for a customer, so everything is tested.
Perhaps the most important part of the Pod, the chassis has undergone some refinements in Pod 3.0. It's a known fact that physical vibration can be a performance killer. Any unexpected movement of a hard drive read or write head requires that drive to spin back around in order to correct the issue. With Pod 3.0, Backblaze has made improvements to the chassis with an eye toward reducing the vibration of the chassis. To that end each row of 15 drives now includes its own anti-vibration assembly intended to address this issue. In addition to helping to keep performance steady, reducing drive vibration can improve disk failure rates.
All told, this 180 TB behemoth costs just under $11,000 to build with 4 TB hard drives. A 3 TB hard drive version yielding 135 TB of raw capacity can be built for $7,567. Backblaze explains that hard drive prices have remained relatively high over the past couple of years, so storage costs are not dropping as they once were, although with the introduction of 4 TB drives, the company is able to squeeze more capacity into a single unit, which provides more storage for less power. In that way, the company can somewhat reduce costs with Pod 3.0. In fact, Backblaze even provides these figures: with 3 TB drives, the company's cost for the storage is 63 cents per terabyte per month on a full-rack basis. With 4 TB drives, this cost plummets to 47 cents per terabyte per month. If those numbers appear too low, they aren't. That's the amortized cost of storage for Backblaze on a monthly basis. The company estimates that the lower ongoing cost for the 4 TB drives means that the more expensive up front costs are recovered in around 5 months.
For me, one of the most impressive aspects of the company is their willingness to openly share their hardware specifications and cost figures. To that end, if you jump to Appendix A in this blog post, you will find a comprehensive list of parts that comprise the Backblaze Pod solution. Bear in mind that Backblaze enjoys some significant economies of scale with regard to procurement, so your own cost may be a bit higher if you decide to try and build one on your own.
From a performance perspective, Backblaze's services are certainly designed to maximize capacity. Data trickles into Backblaze's data centers and traverses the storage infrastructure. As you may imagine, there is significant write traffic and read traffic increases when a customer needs to recover a system. Backblaze is focused on providing very inexpensive but reliable backup space for their customers and they do it well with Pod 3.0.