Just found that the problem is possibly not originating from fstrim.
As hdparm -I /dev/sda reports the error
SG_IO: bad/missing sense data, sb[]: 70 00 05 00 ... I suppose fstrim is just passing the error.
I doubt that it is a real error as my ubunt is a VM with vmfs disk.
Thus fstrim should be silent about the missing sense data at least when the disk has no TRIM capability at all.
Just found that the problem is possibly not originating from fstrim.
As hdparm -I /dev/sda reports the error
SG_IO: bad/missing sense data, sb[]: 70 00 05 00 ... I suppose fstrim is just passing the error.
I doubt that it is a real error as my ubunt is a VM with vmfs disk.
Thus fstrim should be silent about the missing sense data at least when the disk has no TRIM capability at all.