Backup vs. archiving: It pays to know the difference

Computerworld - No organization is exempt from the government, legal and competitive pressures to store more data for longer periods. At the same time, organizations are trying to do more with flat or falling IT budgets.

Storage vendors are introducing a variety of lower-priced storage products designed to meet these new regulatory storage requirements. Wading through these options is becoming a strategic decision that can affect a company's competitiveness, profitability or even its ability to survive regulatory or legal challenges.

Organizations want archival storage products that provide authenticity, long-term retention of data and low total cost of ownership over time, without sacrificing the need for fast access and reliability. However, confusion often arises over the difference between backup and archival storage products and the specific technologies that address each need. Companies must first distinguish between their backup and archiving needs before choosing the appropriate storage solutions to meet those needs.

The difference between backup and archival storage

There is often confusion between a data archive and a backup. A classic backup application takes periodic images of active data in order to provide a method of recovering records that have been deleted or destroyed. Most backups are retained only for a few days or weeks as later backup images supersede previous versions.

Essentially, a backup is designed as a short-term insurance policy to facilitate disaster recovery, while an archive is designed to provide ongoing rapid access to decades of business information. Archived records can be placed outside the traditional backup cycle for a long period of time, while backup operations protect active data that's changing on a frequent basis.

Backup and disaster recovery requirements

• High media capacity






• High-performance read/write streaming






• Low storage cost per GB

Performance is an important factor for backup, but since most backup operations involve large data sets, the ability to quickly stream information to and from the backup media is a first priority. Fast random access to small data sets during restore operations is typically less important. As an insurance policy, it is also necessary to minimize backup expense by reducing the cost of each stored record. The media of choice for backup and disaster recovery applications has traditionally been magnetic tape since it satisfies the performance and cost criteria of most organizations.

Archive requirements

• Data authenticity






• Extended media longevity






• High-performance random read access






• Low total cost of ownership

Archival storage requirements are quite different from those of backup operations. Media longevity and data authenticity feature much more prominently in archive environments. The storage media used within an archive should have a stable, long life to avoid frequent data migration over decades of storage. In order to comply with corporate and government regulations on data authenticity, it is crucial that information be protected from modification.