Courts recognize five categories of data which are discoverable in Federal courts. The pivotal case, Zubulake v. UBS Warburg, LLC, 217 F.R.D. 309, enunciated these categories of data. The first three types of data are considered accessible by the courts, whereas the last two are considered inaccessible.

Active, Online data is usually stored on magnetic discs, such as hard drives. Active data is data that is presently in use or is accessed frequently. It is the simplest data to obtain.

Near-line data that is stored using a robotic storage device, which employs robotic arms to access media. Optical discs are one example of near-line data.

Offline storage/archives are data that is stored in a removable form of media, such as a removable optical disc or magnetic tape, that can be stored on a shelf outside of the computer. Frequently, offline storage is used to make disaster copies or to store data that is not accessed often.

Backup tapes are devices that record data and write it onto tapes. Backup tapes have significant storage capacity of up to several gigabytes. Data is not organized by file, making recovery of documents from back up tapes both time-consuming and expensive.

When data is saved to a computer, it is stored in contiguous clusters. As each file is erased, those clusters become open space. As the remaining files grow, they can expand beyond the contiguous space available on the hard drive. When the files outgrow the space, they are broken up, or fragmented, and the fragments are placed randomly throughout the hard drive. Fragmented, erased or damaged data can only be accessed using computer forensics. Erased data is not truly deleted from the hard drive until the computer writes over the erased data.

For more definitions, please visit our Glossary of Terms page.