Despite reports of supply constraints, the Retina iPad mini appears to be ramping up faster than the original iPad mini. According to a report from Digitimes, Apple ordered nearly 4 million Retina iPad mini units in November, more than the company did last year for the first-generation iPad mini. This follows what appeared to have been major supply constraints. Apple’s supply partners were reportedly having trouble producing enough Retina displays, which at 326 pixels per inch are the most pixel-dense panels Apple has ever made, and CEO Tim Cook admitted that Apple might not be able keep up with demand for the holidays. As a result of the supply constraints, the Retina iPad mini wasn’t released until nearly two weeks after the iPad Air was first made available, and when it was launched, you could only buy it online or with personal in-store pickup. Only in the past week have Apple stores begun selling the Retina iPad mini directly.