Google to disk vendors: Make hard drives like this, even if they lose more data

Google outlines its wish list for hard disk drives that don't exist today but which would be better suited to its needs in the cloud.
Written by Liam Tung, Contributing Writer

Google wants disk vendors to rethink their wares for the cloud, for all hyperscale datacenter operators.

Image: Google

Google wants storage vendors to start building disks for the cloud and to make a clean break from the 3.5-inch hard-drive dimensions inherited from old floppy disks.

Taking a leaf from Facebook's Open Compute Project, Google wants the disk vendors to start thinking about their wares for the cloud to meet storage challenges, not just for Google but for all hyperscale datacenter operators.

So, if disk vendors don't want to see spinning disks relegated to cold storage, Google is challenging them to come up with a new design, optimized for a cloud like Google's.

Speaking at the Usenix File and Storage conference this week, Google VP of infrastructure Eric Brewer made the case for disk vendors to look at its wish list for disks in the cloud, which would involve significantly different designs to the ones used by the current generation of disks aimed at enterprise servers.

Key to Brewer's argument, also outlined in a new white paper, is that video is driving huge demand for disk and that's coming from cloud datacenters operated by the likes of Google, where data is already replicated for failover purposes.

Brewer points out that YouTube users are uploading one petabyte of new storage every day and at current growth rates that they should be uploading 10 petabytes per day by 2021.

"At the heart of the paper is the idea that we need to optimize the collection of disks, rather than a single disk in a server. This shift has a range of interesting consequences including the counter-intuitive goal of having disks that are actually a little more likely to lose data, as we already have to have that data somewhere else anyway," Brewer said in a blogpost.

Specifically, Google appears to be willing to pay a higher gigabyte price for storage, so long as it delivers a lower total cost of ownership as well as higher capacity and higher I/O operations per second.

But as the paper notes, "The industry is relatively good at improving GB/$, but less so at IOPS/GB."

Also, Google isn't interested in SSDs despite their higher IOPS because they cost too much per gigabyte.

As for the alternative to the standard 3.5-inch HDDs, Google proposes taller drives than the standard one inch for 3.5-inch disks and 15mm for 2.5-inch drives.

"Taller drives allow for more platters per disk, which adds capacity, and amortizes the costs of packaging, the printed ­circuitboard, and the drivemotor/actuator. Given a fixed total capacity per disk, smaller platters can yield smaller seek distances and higher RPM, due to platter stability, and thus higher IOPS, but worse GB/$," the paper notes.

Google notes that it does have the scale to order a custom form factor but sees the issue extending to the wider industry and therefore would like to see it standardized.

Security is another area Google wants the industry to work on. The paper points to the very real threat of the government hacking hard-disk firmware, referencing research by Kaspersky Lab into the Equation Group, which did just this.

"It is clear that it must be easier to assure correct firmware and restrict unauthorized changes, and in the long ­term we must apply the full range of hardening techniques already used in other systems," the paper notes.

"We approach this problem in the short term by restricting physical access to the disks and by isolation of untrusted code from the host OS, which has the power to reflash the disk firmware."

It also notes that modern enterprise disks support encryption at rest today, but traditionally with a single key. Google wants finer-grained control using different keys for different areas of the disk.

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