The 19 inch server enclosures are often with the toughened glass doors in the earlier versions of data center, server cabinets with perforated doors are necessary for the approach to work.  For this reason, perforated doors remain the standard for most off-the-shelf server enclosures, though there's often debate about the amount of perforated area needed for effective cooling (In our latest server cabinets AFA series, the perforation is around 67% perforation .)

While doors are important, the rest of the cabinets and racks plays an important role in maintaining airflow. Rack accessories must not impede air input or output. Blanking panels are important as are side "air dams" or baffle plates, for they prevent any exhaust air from returning to the equipment intake (Blanking panels install in unused rackmount space while air dams install vertically outside the front EIA rails). These extra pieces must coexist with any cable management scheme or any supplemental rack accessories the user deems necessary.