External HDD shows very low data transfer rate on different OS

Question

There is a WD Elements 1 TB external hard drive disc that I'm trying to recover. It behaves strange but doesn't show the usual symptoms of a dying hdd (AFAIK). There are no scratching or clicking noises, the disk is spinning (soft vibration) and it gets detected by operating systems (Windows/Linux).

But: the data transfer speed is extremely low. It is possible to copy some files at a very low speed. (<< 1 MB/s). The speed seems to be greater in the first seconds of usage but drops very soon. I tried to do a full disc clone with EaseUS disc copy (booted from USB using UBCD) -> the copying speed is around 5 MB per minute. I tried the same with ddrescue on lubuntu, but it would take forever, too (estimated time ~170 days).

So my question is what could be the cause of this behavior? Is the pcb (2060-771961-001 REV B) a possible cause?

Summary of HDD behavior:

• hard disk is recognised by linux and Windows
• no conspicious noises
• disc seems to be rotating
• extremely low data transfer speed
• speed seems to drop after some seconds of usage
• even cloning the whole disc with dedicated tools is slow

Thanks.

Answer 1

The reason for slowdown may be the number of times the system tries to re-read a block on read failure. You can use a tool such as ddrescue in Linux, which can be configured to "give up" more quickly on encountering a bad block.

As @davidpostill, stated, though, check for issues in S.M.A.R.T. for which you can find explanations online.

Another possibility is failing IC in the external enclosure or a bad power supply (e.g. with AC noise leakage), either which might get worse as they heat during use. You might try putting the HDD itself in another external HDD enclosure, or use a different power supply.

Answer 2

If a SMART log as provided by CrystaldiskInfo or smartmontools does not provide explanations connect a proven good drive to the USB port used for your WD drive to check for interface problems.