Why does backup still matter? (page 1 of 3)

Replication technologies give users access to more recent data, but replication in itself is not enough.

Recovery Point Objective (RPO) and Recovery Time Objective (RTO)


Figure 1. Translating RPO and RTO to technologies.

Backup is the only technology that provides:

• Protection against complete data loss
Traditionally, data protection covers 100% of data within a data centre, whereas replication covers much less, and to replicate all data would be too cost-, storage-, and network-prohibitive.

• Protection against viruses and data corruption
If replication is the only technology used, then viruses and data corruption will simply move from system to system. With backup you are able to go back to any point in time and retrieve a corruption- or virus-free set of data.

• Integrated archival management
Archival management is rapidly becoming a critical issue in most organisations, but by integrating it with backup there are obvious benefits, such as shared use of tape libraries, tracking and reporting of files, and much more.

• Integrated desktop/laptop protection (with DLO)
Protecting the data centre is only part of the equation, and with approximately 60% of all data stored on laptops and desktops (source: IDC), providing data protection across the entire enterprise is more critical than ever. Organisations need an integrated approach to protecting data, regardless of where it is.

• Cost-effective portability of data
Data is commonly stored on tapes, which are easy to move around from location to location. Compare the costs of moving a tape to the costs of moving a storage array and the cost-savings become clear instantly.

• Managed multiple point-in-time copies of data
With disk snapshots you can manage multiple point-in-time copies of data on disk, but sooner or later this will become cost-prohibitive and you will run out of storage. Backup, which is usually done daily, provides point-in-time copies of data going back in time much longer.

Backup, despite its many benefits, does not provide:

• Instant access to data (short recovery time objectives)
Restoring data from tape (or disk) takes time, anywhere from a couple of hours to days or even weeks, depending on how much data there is to be recovered. Even with all the data restored, the systems need to be setup and configured to run as they did before. Clustering, on the other hand, provides near-instant failover of applications from one site to another.

• Minimum data loss (short recovery point objectives )
For organisations requiring immediate access to data backup is not enough, even though backup is the cornerstone of a comprehensive disaster recovery strategy. Replication over IP or mirroring over fibre channel are the only technologies that will give immediate access to data at a secondary location following a complete site outage.

Backup and Disaster Recovery

Most organisations understand the necessity for disaster recovery solutions in today's economy, and as they become more dependent on data and uninterrupted access to data, the financial impact of a system or site outage quickly becomes obvious.

Potential Loss of Revenue by Industry Sector

Figure 2: Downtime can be costly, but more than revenue is at stake when outages occur

What is acceptable exposure to outage is reducing month by month.