Same model, different platter density

[Franc Zabkar]

A WD user recently reported that two Western Digital WD6402AAEX-00Z3A0
Caviar Black drives benchmarked with vastly different transfer rates.
In fact the newer drive tested at 106MB/s vs 133MB/s for the older
drive.

http://community.wdc.com/t5/Desktop/WD6402AAEX-new-drive-slower-than-older-drive/m-p/37755
http://community.wdc.com/t5/Desktop/Check-hard-disk-motor-speed/m-p/40121

HD Tune's access time graphs confirmed that both drives were spinning
at 7200 RPM, so the difference in performance was due to differing
platter densities. In fact the new drive appears to have two 320GB
platters and 4 active heads, whereas the older drive appears to have
two 500GB platters.

http://community.wdc.com/t5/image/s...FC60A7AAD8/image-size/original?v=mpbl-1&px=-1
http://community.wdc.com/t5/image/s...C22A55CA42/image-size/original?v=mpbl-1&px=-1

Furthermore, the new drive appears to have about 20 steps in the
performance curve, corresponding to a full complement of zones. The
old drive, OTOH, has fewer zones, possibly 11 or 12, suggesting that
it has been shortstroked.

- Franc Zabkar

 

[Arno]

A WD user recently reported that two Western Digital WD6402AAEX-00Z3A0
Caviar Black drives benchmarked with vastly different transfer rates.
In fact the newer drive tested at 106MB/s vs 133MB/s for the older
drive.

HD Tune's access time graphs confirmed that both drives were spinning
at 7200 RPM, so the difference in performance was due to differing
platter densities. In fact the new drive appears to have two 320GB
platters and 4 active heads, whereas the older drive appears to have
two 500GB platters.

Furthermore, the new drive appears to have about 20 steps in the
performance curve, corresponding to a full complement of zones. The
old drive, OTOH, has fewer zones, possibly 11 or 12, suggesting that
it has been shortstroked.

Simple, they did a smaller initial production run for the reviewers
and to establish the prodict as high-performance, and then swithced
to a more economic design.

Basically this is fraud and should be something they cannot
do without being criminal and liable. In practice, "product
improvements without notice" are something the customer has
to find out by him/her self.

I once had a run of 25 Intel GbE network cards, exact same
model with consecutive serial numbers but two different chips.
One did run flawlessly under Linux just as the test-card I had
bought, the other 21 crashed after 20 minutes. I had to throw
them away and never have bought Intel networking equipment again.

Arno