The storage racks in Facebook's Cold Storage Facility are Open Compute Project designs with standard spinning disks.
Because the data isn't accessed frequently, the cooling burden is significantly lower than in the main data halls. Here, Facebook keeps the cold aisles a little warmer than its already-toasty production data halls. And rather than implement full-scale data center cooling systems, cold storage takes a modular, compact approach.
The cooling design mimics the systems at work in Facebook's main production halls at the Forest City, N.C. location: no raised floor and no compressor. Free air travels through filters to keep contaminants out, then floods the cold aisles.