What I'm thinking is that there is a, sometimes, delay in the transfer from the external drive to the computer and back to the external drive.
Hmmm, so when I copy a file on P: (the external USB drive) from a folder on P: to another folder on P: (not copying a file from the internal drive of the Notebook to or from P:) information needed to somehow control the (copying) process are delayed (but why is there no error message?) sometimes so it cannot properly be controlled by something that controls the process (in the Notebook, computer)? Actually, something like that was my (really having any idea of anything) thought either. When I plugged in the USB plug the first times the external drive was not shown, after a few times and waiting finally the P: drive was shown. And some time ago with another Notebook (same manufacturer) I had some kind of the same problem: when unzipping / downloading archives to (or on, I do not remember anymore at the moment) a 2,5 external 640 GB drive (A:) sometimes they were corrupted.
And with another older external hard disk, 1TB, some weeks ago I had problems also, the cable USB connection to the Notebook (the same with the P: drive) obviously got interrupted 2 times while copying, I don't know why. May be there is a connection to the P: drive. But other drives appear to work.
Is there a program which could find out if there is such a delay? Crystal Disk Info or such?
My question about file size was - does it make a difference if you copy a small file versus copying a large file?
I do not know at the moment, I didn't try. I just had copied some archives (about 60 MB to about 150 MB) to test. At the moment, respectively since last night I run that "Western Digital Data LifeGuard Diagnostics - DLGDIAG" (http://i.imgur.com/0PIPeaD.png) program to check the drive with the extended option. So I cannot access it. It is displayed to be last until tomorrow, so it will still take a day or so.
What is your operating system and how is that drive formatted? Are there any partitions on the drive?
Win 7, formated the usual way, NTFS. I did a quick format after buying it (full formating lasts about 2 days for 4TB, I guess). No, there is no partition.
Edited by Dirkk, 17 July 2015 - 12:03 PM.