[Info-vax] Odd BACKUP error: unsupported file structure !

[JF Mezei]

Update: I ran an ANA/MEDIA/EXERCISE for a few hours. Not sure if this
ends by itself eventually or if disk was very slow.

I then initialised the suspect drive. I am able to write to it at full
speed.

What I might do is BACKUP/verify to it to see it can reliably read/write

I am torn between declaring the drive hardware-dead or between having
had  corrupted disk structure which caused problems due to an overly big
indexf.sys which may have consume too much memory somewhere etc.