The term to look for is "drive ready time"
Back when 640GB drives were all the rage I pulled the data from three WD drives
Black = WD6401AALS 11 sec
Blue = WD6400AAKS 13 sec
Green = WD6400AACS 14.3 sec
name your drive and you should be able to look up the official specs on the company web site in HTML or in a company supplied PDF.
for the HD203WI (Samsung 2TB F3 Ecogreen) the time is 15 seconds and is pulled from http://www.samsung.com/global/system/bu ... 93f3eg.pdf
Not really hard to find, just have to do it one drive at a time.
Now your actual time to drive ready will vary depending on temperature, humidity, vibration, etcetera but the published specs are readily available if you want to compare an apples to apples time.
Any low power / Green drive is likely to have longer power up times as spinning the disk up quickly takes more power.
HD203WI 15 sec (2TB F3 EG)
HD204UI 13 sec (2TB F4 EG)
WD20EADS 14.5 sec (WD 2TB Green)
WD20EARS ?? sec (I'm guessing 14.x sec like other WD green drives) now that one I had a hard time finding presumably it's the same. You'd probably have to email WD support to get an exact answer.
ST2000DL003 (seagate 2TB green) <15 secs
ST32000542AS (seagate 2TB LP) <16 secs
And of course higher RPM or lower capacity drives will have faster ready times
ST31000520AS <12 secs (1TB Seagate LP )
WD10EADS 14.3 secs (1TB WD Green)
HE103SJ 11 secs (1TB F3R)
WD1002FAEX 11 secs (1TB WD Black)
WD1001FALS 11secs (1TB WD Black)
now look at what happens in the same WD series at 1.5TB and above
WD2002FAEX WD2001FASS WD1502FAEX WD1501FASS all say 21 secs. (1.5TB WD Black and 2TB WD Black drives).\
Ooh, here is a good progression from http://www.wdc.com/wdproducts/library/S ... 701338.pdf
These are all WD RE4 drives
WD2003FYYS 2TB 21 sec (4 platters)
WD1503FYYS 1.5TB 21 sec (3 platters)
WD1003FBYX 1TB 18 sec (2 platters)
WD5003ABYX 500GB 14 sec (1 platter)
WD2503ABYX 250GB 14 sec (1 platter)