After a long haul fixing the Disconnecting and reconnecting bug well reported here and elsewhere now I find that sometimes connecting a 4 or 6 Terabyte external drive to a powered up laptop can cause severe drive corruption which running Windows Check drive for errors can not fix.

I have to leave the laptops powered up so as not to loose the playlist the client was running before my update.

The drive controllers are all those supplied by ICY BOX of Germany at one end and various makes of Laptops at the other, mostly Acer but some Sony, Asus and MSI makes and one Toshiba.   This problem can happen on any of them.   The external drive boxes are always powered down when plugged in and whole directory's containing many thousands of OTS DJ PRO media files can just 'vanish' never to be seen again.

This is happening to only about 2% of the drives in the fleet and it tends to be the same drives each time, but they re partition and format as normal and a Checkdisk surface scan has found nothing wrong.   The names of the drives are similar taking the format of iMS Media Disc 36 where 36 is a unique number between 1 and 42.

These media drives are replaced once a month with updated ones and I run an International Music Services company distributing licensed for playback in Public HD Music Video/Karaoke and Audio to Bars, Clubs, Hotels and other public venues around the World.

From what I have read so far on the Web it would seem that the USB3 standard is not being met fully by the competing manufacturers and us poor consumers are being left to pick up the problem and fix it on our own.   Any Ideas Gang???

I'd suggest that you do a very rigorous anti-malware scan to remove the possibility of the issue being malware on the portable drive.

Although you sound like the kind of person who would have already thought of that....

Indeed but thank you for that, as the chance of a reply to this request is slim at best.   I just wish software and hardware developers would think 'what if'  I am aware of the low chances of some one else having this problem are remote but never the less I have to deal with it and it is time that Microsoft, Intel and all the others in the USB3 project admit that there work is NOT FINISHED.

Are these external drives powered only by the laptop or are they powered up by being connected to an AC adapter? With some laptops, the 5v supply may not have sufficient current capabilities to properly power the external drives. If you have not done so already, I would suggest getting a powered external drive case for the hard drive. Or if you connect the drives through a USB hub, I would use a powered hub.

Yes I have been thinking the same thing as the drives (23 of them) are of various ages and makes and the older ones used to have an external 12V 2 Amp supply where as all the newer drive enclosures now come shipped with a 1.5 amp 12 Volt AC to DC converter and it is just possible that the two or three drives affected require more power on start up.   I update my clients by swapping out the external drive and obviously they do not get the same ones back, the selection being pretty random.

I am being forced to replace all the drives with larger 6 TB types.    I have decided to go for twin raid array icy box enclosures to use up all the existing drives as 8 TB units and fit all the remaining empty ICY box drives with the new 6TB drives, which being modern should handle the 1.5 amp 12 supplies better.

I am very disappointed with the roll out of USB3, in particular the bug which has your laptop attempting to BOOT from the external drive and the other well documented one where the external drive connects and disconnects all the time.  

The online fixes do not work in all cases, either because the Bios is not modern and does not allow you to switch off the USB suspend power saver, or the updating of the usb3 driver does not fix this fault.   With the older 3 to 4 years of age laptops often there is no BIOS update available grrr...  But Windows 8.1 and Windows 10 still attempt to boot from the drive despite the laptop not having any USB3 Ports or drivers.

Manufactures should and must do more to test these new data transfer tools in the field where they will find people like myself running laptops with very large external drives playing promotional HD Music Video's for hours at a time.