Some users claim that the Class 4 SD cards (4 denotes the speed class rating) are more vulnerable to problems, and that upgrading to a Class 6 card fixed that.
Officials said they were prepared to work with unions to resolve any differences but stressed that ID cards would improve security at airports and speed up recruitment procedures.
The Open Compute Project storage page also references Fusion-IO PCIe storage cards with up to 3.2 TB of storage capacity, which are used by Facebook to speed up overall storage system performance.