For a complete list of common StorageCraft terminology, see the StorageCraft Glossary.

Term Definition
Agent-based backup

Installs a software agent on each source system to perform backups. Each agent is semi-autonomous; meaning that it captures the information to be backed up, then stores it at a passive storage location (BDR or destination), as specified in the agent configuration.

A passive destination receives backup information from each agent.

Agentless backup 

A solution that claims agents aren’t needed on each source. An agentless backup solution can be specialized software solution that supports both physical and virtual sources, or leverage host-based utilities to backup VMs running on that hypervisor.

An active control station is the heart of a specialized agentless system. It actively retrieves backup information from each computer being backed up. This type of solution often includes de-duplication and compression software to reduce costs by minimizing the amount of data processed and/or stored.


Literally stands for Backup and Data Recovery but generally refers to a dedicated appliance that acts as a destination for an agent-based backup system. For more information, see StorageCraft's Ray Morgan Company case study.

Centralized Backup Controller or 
Agentless Manager 

The heart of a specialized (not host-based) agentless system.

An active single point of administration used to gather, process, and store data in an agentless backup system. The Centralized Backup Controller backs up an unlimited number of sources on local or remote networks.

Destination  A passive storage location, such as a BDR, where the data is stored in an agent-based backup system.
Filtering A process that intercepts I/O operations intended for a particular kernel driver to perform some sort of pre-processing. The modified I/O operation is then typically forwarded to the intended kernel driver. See also Hooked driver and Hooking driver.
Guest  A VM running in a host environment (hypervisor).
Hooked Driver  A driver that is under the control of, or has had its dispatch table entries modified by a hooking driver. 
Hooking Driver  A driver that takes control of, or hooks, another driver by modifying the other driver’s dispatch table entries.

Also known as a hypervisor. An environment that supports the creation and operation of one or more virtual machines (VM) on a single physical system.

Some Hosts provide tools to assist in backing up their VM “guest” systems. 

IRP Dispatch Table Hooking  A technique used to inject a driver into a running Windows system without requiring a reboot. This technique is explicitly NOT recommended by Microsoft’s kernel engineers because it can cause instability, system crashes, lockups and unrecoverable data corruption.
iSCSI LUN  A logical unit number. A LUN is a separately-addressable drive that is part of a physical SCSI drive. LUNs are effectively numbered disk drives in an iSCSI environment.
Snapshot Driver A Windows device driver which participates in the flow of data to and from storage devices. The snapshot driver adds the ability to create data snapshots to the OS kernel to facilitate backup operations.
Source  Any system (server or workstation) that needs to be backed up. Also referred to as targets, agents, and autonomous agents. 
Tier  A grouping of similar sources in an agentless backup system. Each tier requires its own backup plan, schedule, and policies. Some agentless solutions have up to 7 distinct tiers. 
VSS (Volume Shadow Copy Service A Microsoft service that operates at the kernel-level (below the file system) to prepare (quiesce) applications for backup operations, and create data snapshots used to backup data at a specific point-in-time.

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