Data-protection terms

Asynchronous mirroring — This creates a complete copy of primary data on a secondary storage resource, located nearby or remotely. However, the copy is usually minutes or more out of sync with the primary source.

Backup window — Typically occurring during off-business hours such as nighttime or weekends, this is the time needed to copy data from primary data storage devices, usually disks, to a secondary device, such as tape drives.

Disk-based backup — Backup copies of data are written to inexpensive Advanced Technology Attachment-based disk arrays instead of to tapes, the traditional backup media, thereby capitalizing on disks' superior speed to allow faster backups and restoration of lost data.

iSCSI — This new storage networking protocol allows standard, or block-level, storage traffic to travel through general-purpose IP data networks instead of the specialized Fibre Channel storage networks that are widely used.

Snapshot — Instead of copying the entire dataset like a mirror or clone, a snapshot is a freshly created and separately stored index of pointers that show where primary data is stored at a certain point in time.

Synchronous mirroring — The highest and most expensive level of data protection, this creates a complete copy of primary data in real time on a secondary storage device located close by or a short distance away.

Virtual tape — These products allow disk arrays to look and behave similar to tape libraries to the servers that are initiating a data backup or restore operation.