I am transferring a large number of files (10-100 million) between two external HDDs (connected via USB 3.0), but the external disks are unmounted during the transfer. All HDDs connected via USB (including those on a different port/dock) will be unmounted, not just the HDDs in use.
This problem never happens when transferring a smaller batch of files (e.g., 4 X 5 hours, instead of copying for 20 hours). The problem only occurs when copying takes longer than 10 hours.
There is nothing wrong with the HDDs or files. I frequently checked the disks, and this problem has happened for more than ten different HDDs (all EXOS Enterprise 18TB).
I tried GUI cut/paste, cp
, rsync
.
How can I diagnose the problem to resolve it? Any hit would be sufficient; I do not expect a full solution.
Hardware: Taichi X399 Motherboard with Threadripper 1950X CPU. The filesystem is ext4
.
There are, of course, many I/O errors in syslog, but I believe they are a result of the unmounted device rather than the cause. The first pertinent errors are:
Jan 30 12:54:07 ubuntu1 kernel: [22033.966192] xhci_hcd 0000:0c:00.3: xHCI host not responding to stop endpoint command.
Jan 30 12:54:07 ubuntu1 kernel: [22033.966203] xhci_hcd 0000:0c:00.3: USBSTS: 0x00000000
Jan 30 12:54:07 ubuntu1 kernel: [22033.983466] xhci_hcd 0000:0c:00.3: xHCI host controller not responding, assume dead
Jan 30 12:54:07 ubuntu1 kernel: [22033.983493] xhci_hcd 0000:0c:00.3: HC died; cleaning up
Jan 30 12:54:07 ubuntu1 kernel: [22033.983581] usb 4-1: USB disconnect, device number 2