You might not be aware, but we are in the terabyte era. Though it’s been somewhat overshadowed by advances in Cloud Storage Technology, hard disk drive manufacturers are still pushing ahead with increasing capacities. Remember the drives with storage capacity of 4TB or even 6TB that seemed so massive just a short time ago? Well, Western Digital’s HGST subsidiary announced the world’s first 10TB hard drive less than a month ago. HGST’s 10TB drive is an enterprise series, a data center class storage device, intended for cloud and cold storage applications. HGST hopes their new drive will set the bar with both the lowest watt-per-terabyte and price-per-terabyte, but have never revealed the specific metrics. The drive uses SMR and HelioSeal technology to deliver this unprecedented capacity.
HGST’s HelioSeal is helium-filled and is an obviously hermetically sealed drive. This design has higher capacities and yet maintains significantly lower power and cooling requirements with improved storage densities.
Their 8TB Ultrastar He8 helium-filled hard drive is currently shipping. It delivers 33 percent more capacity and 23 percent lower power than HGST’s 6TB drive and like the 10TB model is intended for data center applications.
Shingled Magnetic Recording and the First 10TB Hard Drive
Shingled Magnetic Recording means that relatively wide tracks are written to the disk and successively written data tracks partially overlap the previous ones, similar to the manner roof shingles are applied, hence the name. A key component of increasing data density in HDDs is in making thinner data tracks and packing them closer together. Writing narrower tracks has always meant narrowing the width of the poles of a tiny magnet on the read/write head. When energized, a magnetic field emanating from the poles writes and erases data by flipping the magnetization of small regions, called bits, on the spinning disk directly below. But narrowing the poles also reduces the strength of the writing magnetic field, so they can’t be shrunk to the point where the field can’t flip a bit’s magnetization.
HGST achieves greater data-density by writing relatively wide tracks that partially overlap the previous ones. If executed correctly SMR is expected to enable data densities as high as 3 trillion bits per square inch!
In practice, SMR’s overlapping tracks are best suited for continuous writing/erasing rather than small random-access updates. In certain cases, a more ideal solution would be to designate part of a disk with high-density shingled tracks for storing log files while leaving the remaining part un-shingled to permit more rapid random access at lower data density. This is expected to be solution for cheap Archive Drives.