Two external volumes that are both having I/O errors. This is a small bit of console output. One is an SSD and the other is a regular hard drive. Both are relatively new.

default 18:46:56.035095 -0800   kernel  disk2s2: I/O error.
default 18:46:56.084555 -0800   kernel  disk3s2: I/O error.
default 18:46:56.133860 -0800   kernel  disk2s2: I/O error.
default 18:46:56.182963 -0800   kernel  disk2s2: I/O error.
default 18:46:56.232262 -0800   kernel  disk3s2: I/O error.
default 18:46:56.288224 -0800   kernel  disk2s2: I/O error.

What would explain I/O errors for two different volumes?

Both are directly connected via a USB-C hub. The same problem occurs when they are each separately connected via a USB-C to A cable to my MacBook Pro.

Every diagnostic tool I have tried says the drives are fine. This includes Techtool Pro, Drive Genius and DiskWarrior. Console shows no I/O errors while these tools are doing a surface scan or rebuild.

When they are first mounted both drives appear normal, but after 30-40 minutes they both remain mounted but all the files are missing from the Finder window. du -h from a terminal shows all the top level folders as being empty but no subfolders. After remounting each drive all the files are intact.

Is there any way to rule out/in hardware issues and if so how? Could it be an HFS/AFPS issue? Both drives are HFS but the startup volume is AFPS. At this point I don't think it is the drives themselves.

  • this is a far fetch, but there are some reports of Interference between USB-C and WiFi, Try additional shielding (Al-tape for the cable) – Ruskes Mar 3 at 6:07
  • 1
    I would check out cable / connector issues - is it with 1 port or all ports - is there dust / dirt or are they loose? – Solar Mike Mar 3 at 6:54

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