The technology overlap between backup, redundancy and archiving can often lead to confusion, but each has a different role to play in streamlining and safeguarding data. Backups essentially create a second copy of data at specific points in time, ideally keeping multiple historic copies. Redundancy establishes a straight copy of an entire system, ready to take over if the original system fails. Backup offers a certain level of redundancy, and redundancy a basic level of backup, but neither are stand-alone solutions.
Archiving makes a primary copy of selected data with the aim of retaining data in the long-term. Not all of the data contained in a backup will ultimately end up in an archive so archiving is rarely an adequate backup solution in itself but as a complementary approach, it can considerably optimize the data storage process.
Most backup strategies rely on a combination of backup, redundancy and archiving. An important factor to bear in mind when planning a backup schedule is prioritization of data. Not all data is created equal and a tiered backup strategy that restores the most critical applications first will get you back in business faster and cut data storage costs.
- A full backup copies every file in a system. Restore times are fast but backups are time-consuming and space-intensive so scheduling and data prioritization are important considerations.
Differential / Incremental
- Differential and incremental backups fill in the gaps between full backups, storing any changes to data. They require a fraction of the server CPU cycles, bandwidth and storage space. The risk of data loss is obviously greater than full backups and restore times are slower but Infrascale can use special snapshot technology such as Block Level de-duping to rebuild images more rapidly.
- A synthetic backup consolidates a full backup and subsequent incremental backups into a single file. Recovery is fast, using less server cycles and bandwidth.
Continuous Data Protection
- In contrast to scheduled backup, continuous data protection (CDP) continuously tracks data modifications. CDP saves all changes and data can be recovered rapidly from any point in the past. Bandwidth burden is considerable but using compression techniques and block-level incremental backup, CDP devices can significantly reduce this load.
- Mirroring is a redundancy solution that literally mirrors your systems by making a straight copy of data to two or more drives simultaneously. Thereafter only new and modified files are copied. Unlike a full backup, data is not usually compressed so recovery is faster.