Drobo

Data protection takes the second time a very long time

my van was broken of the drobo 5d, so i got a new drobo, but the drobo did not work. so i got an secodn one, but the fan was again a problem. the data protection was about one hour. so i had to send it back. the third one: the first time i put 5 drives of 8 tb in my drobo 5d, data protectrion took about 1 hour. i had to take them out, and now i inserted them again, and it takes 37 hours! why is it so long the second time? did anyone has this problem?
thanks