I'm selling a computer with an SSD (it's a Lenovo ThinkPad Carbon X1). I wiped the drive using Parted Magic. I used the ATA method. I'm not sure what that is but it was the only setting available. It said it would take two minutes but the wipe was done in a few seconds. Is this expected behavior? It's not a major issue as the drive was encrypted with VeraCrypt, but I'm curious for future reference.
Modern SSDs use a technology called SED which allows instant erasure. It works by transparently encrypting the entire drive and keeping the key on the drive. ATA Secure Erase is then implemented by wiping the key alone, which renders the rest of the data immediately unreadable (assuming of course that it has been correctly implemented on that particular storage device). The reason two minutes specifically is quoted is because it is the minimum value the ATA protocol can report.