Red light mystery

Red light is on for a drive that seems - so far - to be working perfectly well.
I have been around computers too long to ignore a red led. They end up biting you.
Any advice what it can be?
Thanks

When the red light came on, it was the chip that found the error in the hard drive.

Some of the errors are not fatal and will not affect your files, so it works fine for now.

You can use smartctl to check the hard disk information, but you need to do two things before that.

  1. Download smartmontools-7.1 and compile it. The version in the apt is too old.

  2. Upgrade the firmware. The factory firmware shows something wrong with S.M.A.R.T. .

Thanks setq. Will try smartctl.
I must say I have stability issues with the NAS, at the moment, but working through them. I can’t cp more than 200 or 300GB between to drives without one of the drives disconnecting… If it persists I’ll open another thread on this forum, but do you have any immediate hint that come to mind?

I faced a red light some time ago as well.
The HDD was not mountable as the master boot record was destroyed by simple (and thoughtless) replacing cp with pv (without >) in cp /mnt/v1/a.tmp /mnt/v2 to measure performance.
You should check your file system structure of that disk.
I did not had a red light when I destroyed only a directory (pv /mnt/v1/test/a.tmp /mnt/v2/test).
In that case all reads were OK,
but write attempts to that dir throw an IO error message on console,
but interestingly there was reproducable NO indication in dmseg.

Thanks @michael. fsck passes on the disk, but still not comfortable with an outstanding red light… the disk also grinds (I mean heads are moving) when it shouldn’t, and for a long time at boot. Something amiss, just haven’'t found out…