Most of today's 2.5" notebook hard drives top out at an even terabyte. You can find higher-capacity offerings, but those conform to 12.5- and 15-mm versions of the 2.5" form factor, which are meant for external enclosures and are too fat to fit in most notebooks. HGST's Travelstar 5K1500 is different. Announced today, the drive squeezes 1.5TB into a notebook-friendly 9.5-mm case.
The 5K1500 is not only the first standard notebook hard drive to bust the terabyte barrier, but also the only 9.5-mm design with three platters. 9.5-mm drives have thus far been limited to two platters, and HGST had to make several changes to accommodate the third disc. According to VP of Product Marketing Brendan Collins, the drive's electronics package was shrunk by half, in part thanks to the move to BGA chip packages. The circuit board is now small enough to avoid overlapping the platters, leaving room for another.
In addition to shrinking the electronics, HGST also tweaked the mechanical components to provide extra room for the platters. The end result is a three-disc stack with the same platter spacing as the firm's existing two-disc variants. Because the spacing hasn't changed, shock tolerance purportedly isn't an issue. The 5K1500 has the same shock specifications as HGST's two-platter 5K1000.
Unsurprisingly, the 5K1500's 500GB platters are identical to those of its terabyte sibling; they have an areal density of 694 Gb/in². Data is accessed with a dual-stage actuator, which we've seen on several of HGST's 3.5" desktop and enterprise drives. This appears to be the first time the firm's ultra-precise actuator has been employed in a notebook model, though.
As the model number suggests, the 5K1500 spins its platters at a sedate 5,400 RPM. Collins told us there are no plans for a 7,200-RPM variant, which is unfortunate but understandable given the platter density. He expects the 5K1500 to be paired with a caching SSD that blunts the performance impact of its slower rotational speed.
The Travelstar 5K1500 does have some built-in cache, but it's a more traditional DRAM chip that weighs in at 32MB. That cache size is actually pretty generous for a notebook drive; most have only 16MB of onboard memory.
Starting next month, the 5K1500 should start popping up in pre-built notebooks and as a bare drive sold through outlets like Amazon and Newegg. It's undergoing qualification testing with notebook makers right now. In the third quarter, the standard model will be joined by an enterprise-friendly EA variant, which will have a few extra features and will be subject to extra validation testing. A version of the 5K1500 with TCG Opal-compliant self-encryption is due in the third quarter, as well. The EA and self-encrypting models will use custom firmware, but they'll have identical hardware to the standard 5K1500.
This isn't the first time HGST has reached a capacity milestone by using more platters than the competition. For years, the firm's high-capacity desktop drives have used five platters, while most competing solutions have stuck with four. Collins told us that increasing the number of platters means HGST can be more conservative when pushing areal densities. The company can bring new capacities to market faster, he said, and "reliability tends to be much higher."