Adisk packis a layered grouping ofhard disk platters(circular, rigid discs coated with amagneticdata storagesurface). A disk pack is the core component of ahard diskdrive. In modern hard disks, the disk pack is permanently sealed inside the drive. In many early hard disks, the disk pack was a removable unit, and would be supplied with a protective canister featuring a lifting handle.

The protective cover consisted of two parts, a plastic shell, with a handle in the center, that enclosed the top and sides of the disks and a separate bottom that completed the sealed package. To remove the disk pack, the drive would be taken off line and allowed to spin down. Its access door could then be opened and an empty shell inserted and twisted to unlock the disk platter from the drive and secure it to the shell. The assembly would then be lifted out and the bottom cover attached. A different disk pack could then be inserted by removing the bottom and placing the disk pack with its shell into the drive. Turning the handle would lock the disk pack in place and free the shell for removal.

The first removable disk pack was invented in 1961 by IBM engineers R. E. Pattison[1]as part of the LCF (Low Cost File) project headed by Jack Harker. The 14-inch (356mm) diameter disks introduced by IBM became ade factostandard, with many vendors producing disk drives using 14-inch disks in disk packs and cartridges into the 1980s.