Highly Reliable Systems: Removable Disk Backup & Recovery

Largest Hard Drive to use Heat-Assisted Magnetic Recording for 6.4TB

By Tom Hoops

Could 6.4TB become the largest hard drive in the near future? A few months ago we reported that Western Digital was working on a large format hard drive that would be filled with helium to reduce drag and friction.  We speculated the size would be in the 5.6TB range.  There are 2 other key technologies on the horizon for increasing Areal density.  The first is called Shingled magnetic recording (SMR), which is the overlapping of data tracks to cram more tracks and hence more data onto a drive’s recording surfaces.  The second is Heat-Assisted Magnetic Recording (HAMR).  These techniques are being used by Seagate to push hard drives past the 4TB size they’ve been stuck at for the last several years.  The current perpendicular magnetic recording (PMR) technique is reaching it’s density limit.  Any attempt to reduce the size of the magnetic bits results in instability. SMR drives could begin shipping in late 2013 and enable a 20 – 25 per cent areal density increase. Taking a 4TB 3.5-inch drive and giving it an SMR upgrade would bump capacity up to 4.8TB to 5TB.  However SMR drives take longer to rewrite data because tracks overlapped by the new data track have to be reconstructed before the new data can be written. Sometime in 2014 Seagate hopes to introduce the even more sophisticated HAMR technology.  A tiny laser is added to the read/write head to quickly heat up spots on the disk.  Creating a trillion bits/in2 areal density a 4-platter 3.5″ HAMR drive could store up to 6.4T.  Seagate speculates that using HAMR with continuous improvements over the next 10 years could eventually produce a 60TB drive.

2 Responses to Largest Hard Drive to use Heat-Assisted Magnetic Recording for 6.4TB

  1. Moe Sukhon says:

    Hello Tom,

    Do you know what impact would increasing recording density have on the design of the HDD preamplifier? Do we expect more stringent linearity/SNR/speed requirements to be imposed?


    • Tom Hoops Tom Hoops says:

      Hello Moe,

      Not being directly involved in the design of these I can only speculate. But if recording density increases and there is no change in encoding methods and physical read rates (RPM, etc) remain constant, it only stands to reason that signal frequencies will increase. Thus, the typical design differences and techniques necessary to increase amplifier response (higher impedance, lower inductance, better linearity, lower offset, etc…) would seem to apply, unless there was already enough headroom in current designs.


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