E-Discovery Categories of Electronically Stored Information

By Linda Volonino, Ian Redpath

Part of E-Discovery For Dummies Cheat Sheet

In e-discovery, electronically stored information (ESI) is divided into five categories, which are grouped into two tiers based on the effort and cost needed to access ESI. Keep these categories in mind when requesting ESI or responding to a request:

Category What It Is Accessibility
Active, online data ESI created, received, or processed; or that’s quickly
and frequently accessed. Examples: hard drives and
active network servers.
First tier: reasonably accessible
Near-line data (short for near online) ESI stored on removable media or accessed via automated or
robotic storage systems. Access speeds range from a few
milliseconds up to 2 minutes. Examples: optical disk
and magnetic tape.
First tier: reasonably accessible
Offline storage and archives ESI sent to storage. Unlike the first two categories, offline
ESI is accessed manually. Examples: magnetic tape or
optical disks; referred to as JBOD (just a bunch of
First tier: reasonably accessible
Backup tapes, commonly using data compression ESI stored for backup or disaster recovery and not organized
for retrieval of specific files or messages. Retrieving ESI
requires restoring the entire tape and might require reversing the
compression used to fit more bytes of data. The discovery of ESI
from backup tapes requires proof that their need and relevance
outweigh their retrieval and processing costs.
Example: backup tapes.
Second tier: not reasonably accessible
Erased, fragmented, or corrupted data Erased, overwritten, fragmented (broken up and stored in
separate areas), or corrupted files (damaged by computer viruses,
or a hardware/software malfunction) are the least accessible. This
ESI might be accessed only after significant processing or might be
impossible to access at all.
Second tier: not reasonably accessible