What is Unallocated and Slack Space on a Computer Hard Drive?

Generally, under both federal and state rules of civil procedure, parties are obligated only to produce electronically stored information (ESI) that is reasonably accessible.  For instance Fed. Rule Civ. Proc. 26(b)(2)(B) provides that absent good cause, “[a] party need not provide discovery of electronically stored information from sources that the party identifies as not reasonably accessible because of undue burden or cost.”  Some courts consider several types of data not generally discoverable in litigation, including “deleted,” “unallocated,” “slack,” and “fragmented,” data.

Deleted files may create unallocated space on a hard drive.  When a computer file is deleted, it is not erased from a hard drive. Instead, the space occupied by the deleted file becomes “unallocated” and available for saving other data.  Slack space is another source of unallocated space on a hard drive. Slack space is created when only a portion of space allocated to save information (called a cluster) is used. For instance, say a file size is 25 kb and the computer allocates a 32 kb cluster in which to save the data.  The unused portion is “slack” space.

Understanding various types of hard to collect data will assist during ESI protocol negotiations and early e-discovery meet and confer conferences with opposing counsel. Counsel can discuss what file type are hard to access and enter into agreements about what data types will not be produced.