[PaulHoule]

There was that time (2009 or so?) I wrote 2 million files to a single directory on NTFS and that filesystem was never the same again. It didn't seem to be a hardware problem. I used to be really careful to not put a crazy number of files in a directory on Linux and Windows storing them in subdirs like

  b7/b74a/b74a56

where the digits are derived from a hash of the file name but lately I've had some NTFS volumes with a 1M file directory that seem to be OK.

Hardware problems also manifest in mysterious ways. On both Windows and MacOS I had computers that seemed to be OK until I did an OS update which caused enough IO that a failing HDD was pushed over the edge and the update failed; in one case I was able to roll back the update but not apply the update, in another case the machine was trashed. Careful investigation (like taking the disk out and inspecting it on another computer) revealed a hard drive error although there was no clear indication of this in the UI and the average person would blame to software update