Specifications

WD20EADS Caviar Green Overview

The RE4 shares many of the features present in the Caviar Green 2TB
line.  Carried over from my previous piece, where I attempted to
translate the marketing speak:

• IntelliPower™ — GP drives consume less power with slower
  spindle speeds, performance drop is offset by larger caches and higher
  platter densities.
• IntelliSeek™ — Seek speeds can change
  'on the fly', since the heads do not always need to be moved at full
  speed to make it to the data before it rotates past.
• NoTouch™
  ramp load technology — Previously called "IntelliPark".  Drive heads
  take an 'exit ramp' off of the platters instead of landing on the
  platters when the drive is spun down.  You know how the most damage is
  done to your engine when you start it on a cold morning?  This means the drive heads do not have to break stiction each and every time the drive spins up.  The heads are able to leave the ramp and float onto the spinning disk.

• StableTrac™
  — The spindle is supported at both ends instead of only at the bottom,
  keeping the platters more stable during reads and writes.

• Native Command Queuing (NCQ) — The drive can
  reorder groups of reads/writes to minimize overall head movement, and
  therefore increase effective access time.  Beware - this is only
  effective with an AHCI-enabled SATA controller.

• Perpendicular Magnetic Recording (PMR) — Bits
  are aligned vertically instead of horizontally to get more packed onto
  each platter.  Think dominoes (the game, not the food).
• Low
  power spin-up — Lower RPM's mean less power when trying to get to
  target speed.  These drives also accelerate slower during spin-up as to
  draw even less power.

Here are some features unique to the RE series drive (translated by yours truly):

• 64MB cache — Up from 32MB for the Caviar Green, this should help out with random access performance.
• Dual processors (!) — Yes, welcome to the worlds first dual core 3.5" hard drive.  Multiple CPU's should help out in the area of IOPS performance, as well as juggling around all of that cache memory.

• RAID-specific time-limited error recovery (TLER) — The drive
  limits the 'hang' experienced on a read error in order to avoid a RAID
  controller considering the drive dead / offline.
• Rotary Acceleration Feed Forward (RAFF™) — I've got nothing.  Just kidding.  More on this near the end of the article. 

The RE4 is much more different on the inside than you might think.

So will the added marketing speak translate into real gains in
performance?  Onto the benching to find out what makes this puppy
tick... 

Testing Methods

Our tests are a good mix of synthetic and real-world benchmarks. 
PCMark, IOMeter, HDTach, HDTune, Yapt and our custom File Copy test round out
the selection to cover just about all bases.  If you have any questions
about our tests just drop into the Storage Forum and we'll help you out!

Test System Setup

• PCMark05
• Yapt
• IOMeter
• HDTach
• HDTune

• PCPer File Copy Test