Backup to protect data
Definition
A backup is a security copy of stored data on another medium such as SSD or hard disk, CD-R, tape or in the cloud. This is to protect against software problems, data loss due to hardware failure, external threats, natural disasters or malware. Even the backup can be affected by data loss, which means you always need more than a single copy.
Standard procedure
Full backups are usually only used for databases or in development environments. The amount of data is limited here and can be easily calculated. With several million unstructured data, data volume and data transfer rate can no longer be brought into a calculable relationship.
Above a certain data volume, the backup volume must be reduced. Full backup can therefore be combined with differential backup or incremental backup. Continual Data Protection (CDP) and read-only snapshots have also proven their worth. If this is not sufficient, deduplication is a proven solution, which is often combined with a compression method. Global deduplication and CBT (Change Block Tracking) are added as modern procedures.
Incremental backup
With incremental backup, the archiving flag is used, which is only reset after the files have been written again, so that files are included in the backup cycle again. With the restore, after the last full backup, each partial backup produced afterwards must be copied back in the correct order.
Differential backup
The differential backup saves the user from having to copy numerous increments in an emergency. For all backups, all processed data is saved from the last full backup.
Snapshots
Backing up data to tape takes some time, during which new data is usually already being generated. A snapshot, which can be taken at frequent intervals or shortly before an intervention in the system, provides a remedy. Snapshots are not really data backups, but notes about which file blocks have been changed since the last snapshot was taken. Either old data is moved to other locations and new data takes its place or vice versa. As snapshot mirrors, snapshots can also copy the entire files to another storage system as a background activity.
