Amazon may be using disk drives with hot-swappable components

Patent calls for drives in which mechanical bits and electronics aren't bound together

A figure from Amazon's patent for de-composed disks
Amazon's illustration of how de-coupled disks might work

Amazon's won a patent for “Hard disk drive assembly with field-separable mechanical module and drive control”.

In Amazon's world disk drives have two distinct systems. There's a “drive mechanical module” comprising a drive's arms, heads, spindle, motor and platters. And there's a “control module”, basically the drive's motherboard.

But as the patent notes, when disk drives fail “Many hard disk drives failures may only involve electrical components (such as a semiconductor chip failure) or only mechanical components (such as an actuator failure). Nevertheless, repairing the data storage system may require removing and replacing both the mechanical components and the electrical components of the hard disk drive.”

Amazon would rather replace one or the other, rather than a whole disk. Hence the patent application's proposal for disks that the mechanical module or the control module be replaceable. And replaceable in situ without having to remove a disk from a rack.

The application also proposes a rack-mounted system in which control modules and mechanical modules could be discrete. It's even suggested control modules could serve more than one mechanical module. Building a whole-of-rack system around this idea is said to facilitate easier non-disruptive replacement of either and also offers some cooling advantages.

Amazon filed this patent in 2012 and it appears to have been granted earlier this year and to have bubbled into public view in recent days.

There's no indication the company has adopted this technology, but it would not surprise if it has done so given the scale at which it operates and the advantages this approach to disk design confers. It's also likely a cost saver as parts could be cheaper than whole new disks. Being able to replace a disk drive's motherboard could mean data could be retained with a slight dip in resiliency while a new board is pressed into service.

Amazon's not alone in wanting exotic disks: Google last year called for disk-makers to build taller drives that fit more platters. Apple's also added extra pins to drives for the iMac, which irked users as it meant off-the-shelf kit would not work in their computers and Cupertino's replacements sold well above market prices.

Disk-makers didn't rush to help Google – in public at least – but Apple had no trouble getting what it wanted, suggesting that if Amazon has, or does, seek its de-composable drives it won't have much trouble finding someone to build them. ®

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