Wiping 2 internal drives in a Mac Pro
I have a late 2010 Mac Pro with 1 - 1T SSD drive and 2 - HDs. The SSD is the startup drive. I want to wipe securely the 2 - HDs and take the SSD out before giving to charity. I tried to use the Disk Utility within the SSD and wipe the 2 - HDs but all the data still seems to be there!?? What's the most effective (time with security) way to wipe the 2 - HDs and install the OS on at least 1 - HD? Thank you!