HDD appears much smaller than its factory size

Question

I recently bought a used 2TB WD Green (WD20EADS) hard drive at a hamfest. The problem is, I've tried it on two different computers (described below), and neither one is able to detect it as a 2TB drive. Depending upon which program I ask, its size has been variously reported as "1191.97GB", "1280GB", and 1,220,575 megabytes.

I know it's not going to show up as "2,000 gigabytes", but I also know that the kB-vs-KiB difference isn't going to account for a loss of ONE THIRD of the drive's nominal capacity.

Computer #1: Asus P5N-D motherboard (latest BIOS, circa 2010) running Windows 7 Pro (64-bit).

Computer #2: Dell Precision m4800 laptop (circa November 2013) using Orico USB3.0 dock ( https://www.amazon.com/gp/product/B00CE65C4W ) running Windows 10 Pro (64-bit). I've successfully used this dock on this computer to connect 4TB drives, so I'm pretty confident that the controller in the dock is working fine. Furthermore, I actually HAVE a 2TB 2.5" internal hard drive (along with a 512GB mSATA card), so I'm quite confident that THIS computer can handle 2TB drives just fine.

• S.M.A.R.T. (via WD Data Lifeguard) claims there's nothing wrong with the drive (I considered the possibility that it might have silently written off an entire platter due to failure… but if that's what happened, the app's not admitting it).

• I did a full erase using Western Digital's Drive Lifeguard diagnostic program. No change.

• I tried jumpering pins 5 and 6 (to force 1.5TB PHY) and rebooting. No change.

• I've tried changing between GPT & MBR and rebooting. No change.

The problem with computer #1 didn't particularly shock me (it IS, after all, kind of old), but the fact that it exhibits the exact same problem on a newer computer running Windows 10 WAS a complete surprise.

I'm completely stumped. What else could cause a 2TB drive to be seen by Windows as a much smaller drive than it actually is (on a computer that has dealt with MUCH larger drives in the past without problems)?

Answer 1

Research HPA. It can make your drive appear smaller. From Wikipedia:

The host protected area (HPA) is an area of a hard drive or solid-state drive that is not normally visible to an operating system. It was first introduced in the ATA-4 standard CXV (T13) in 2001.

In Linux the right command to check if HPA is enabled is hdparm -N, e.g.:

sudo hdparm -N /dev/sdx

The same hdparm will let you change or disable this setting. Invoke man hdparm and read about the -N option. Note there is a volatile and non-volatile mode.

There should be similar tool(s) for Windows. The mentioned Wikipedia article links to ATATool; seems useful, I have never used it though.

Answer 2

Assuming that:

• You have confirmed the drive identifies itself as a WD20EADS with the tools you mentioned. (Could be a fake)
• You are properly interpreting the tools you mostly didn’t name.
• You have tried a tool like DBAN to completely wipe the drive.

I don’t have any issue with saying the drive is simply bad. Probably a firmware issue.

Answer 3

That drive size does not exist from any manufacturer.

The WD20EADS has an effective size of 1862.65 GB (aka GiB). There is no controller or software error that would cause the drive to show 1191.97GB. There are many controller problems above 2TB, which is not the case for you.

Does the size show correctly at boot time (BIOS/UEFI screen) ? If it does not, there may be something wrong with the HDD firmware. Try updating the firmware and if that doesn't fix it, you should RMA it.

During any further testing, do not use any jumpers anywhere.