Many people misunderstand how "digital storage" works, especially in reference to the Correlated storage system. They seem to believe that the items are turned into data and annihilated, later to be reformed based on the saved data. This is not correct — if it was, infinite copies of any given item could be created at no extra cost.
Rather, Correlated storage is based on Ender, a very interesting substance which, at its core, allows transport of matter or energy to and from "Enderspace" — a seemingly infinite in-between space generally used for teleportation by Endermen. Humans may also harness this by taking the concentrated "pearls" of Ender, dropped by Endermen when they die, and throwing them hard enough that they shatter. For reasons that still elude us, this causes the thrower to temporarily shift into Enderspace and then back out where the pearl shattered.
Enderspace also has uses in storage; combining an Ender Pearl with Blaze Powder allows creating an Ender Chest, a limited size portal to a personal slice of Enderspace. Curiously, two people opening the same Ender Chest won't see the same items, as the region of Enderspace accessed is based on who is doing the access. Consequently, only living creatures can use Ender Chests. A computer, or more primitive device such as an iron hopper, cannot use an Ender Chest.
But, what happens if one combines an Ender Pearl with other kinds of powder? A variety of effects can occur, but the most interesting for our purposes is Glowstone Dust, collected by smashing the glowing crystals that grow on the ceiling of the Nether. Glowstone is already known to cause erratic behavior in Redstone circuitry, generating seemingly random output. The same kind of behavior manifests when combined with an Ender Pearl — sending matter or energy through a Luminous Pearl (i.e. an Ender Pearl with Glowstone Dust on it) causes it to be sent to a random place in Enderspace.
This is not normally useful. If matter or energy is sent to a random place in Enderspace, there is no way to retrieve it! However, a Luminous Pearl emits small amounts of radiation that correspond directly to where the item was sent in Enderspace. This location can be stored on normal storage mediums and later be used to retrieve the item again!
This is the core of the Correlated storage system — items are sent to Enderspace, and their locations are stored on normal hard drives. This is why a Correlated drive requires both a drive platter and a Luminous Pearl — they serve different purposes.
Later, the platter can be forced into the Luminous Pearl creating a Data Core. By shattering a Data Core, all of the matter and energy previously stored in Enderspace at the stored positions are released immediately at the point it was broken.