Backup/recovery

Backups are stored on disk or tape, often being written to disk first before being stored on tape for offsite, long‐term storage. Backups should be kept separate from the production site in order to facilitate disaster recovery.

Extension modules for backup/recovery are available for integration with the most common applications and databases.

Why?

When designing a backup/recovery solution, it is important to consider the Recover Point Objective (RPO), the Recovery Time Objective (RTO) and the Service Level Agreement (SLA) requirements before choosing which method to use.

Recovery Point Objective – RPO

The RPO is the point in time (prior to a failure) to which you must recover data as defined by your organisation.
This could also be expressed as “how much data we can afford to lose in the event of a failure/disaster”.
A definition: The maximum desired period prior to a failure or disaster during which time changes to data may be lost as a consequence of recovery. Data changes preceding the failure or disaster by at least this time period are preserved by recovery. Zero is a valid value and is equivalent to a "zero data loss" requirement.

Recovery Time Objective – RTO

For how long can we allow one or more applications or systems to remain unavailable?

This can be defined as the maximum desired period required to restore one or more applications and their associated data to a correct operational state.

LAN backup

This is the most common way of backing up data; it is well known and supports almost every commercial operating system on the market. It is fairly easy to implement and manage. Each server has a backup agent installed and the data is transferred over the network to the backup server. Use of a dedicated backup network is recommended. Backup and restore performance are in most cases limited to the bandwidth of the network.

LAN-free backup

This method is also referred as SAN backup. In this case, the servers have a media server/storage node installed instead of the regular backup agent. This allows the server to transfer data directly to the backup device (disk or tape) without using the LAN. The backup and restore performance are the advantages of this method. It is employed on servers containing a large amount of data and/or for mission-critical systems requiring fast restores.

Snapshot-based backup

With a snapshot-based backup solution, it is possible to eliminate traditional backup software. One of the biggest benefits of this is the option of running backups more frequently; every hour, for example, instead of just nightly. Replication of snapshots to a secondary system is highly recommended so as to avoid losing data in the event of a disaster. This technique requires storage systems that can accept and store a lot of snapshots without impeding performance.