invisible data ??

data replaced by bootsqm.dat file !!!!!

ok my system has an sata drive caddy

now for some reason every drive i place in the caddy has this bootsqm file on it and nothing else !!!!!!! when i look at the drive unopened from my computer it shows the drive full as it should be but when i open the drive all i see is the bootsqm file and nothing else ,,,, this is the same no matter what drive i put in the caddy the all look the same

does anyone have any idea what this is about

thanks