How Continuous Backups Work
A new CDP server executes a full backup to disk of the all server data, initialising itself with a complete data set. After that, the CDP server will execute frequent incremental backups at designated intervals – every five minutes, every hour, whenever a log changes in your email or database system – whenever you want. These new technologies have redefined ‘incremental backup’ to mean only the actual changes in each file – instead of the entire changed file – are backed up. Less data means backups run much faster, and you can backup more frequently because the overhead of each backup is significantly reduced. For example, if you lose a file at 4pm, you don't have to go back to yesterday's version – you may have a 3pm version, which significantly reduces lost work and lost productivity. You gain dramatic improvement in backup frequency, increasing fidelity without hurting performance or increasing administrator burden.
Another improvement is that the backups are application – and file system-consistent. CDP products are aware of the objects they are backing up – files, email messages, etc. – so both users and administrators are presented with familiar objects during restore. Restore is immediate – no lengthy process is needed to place data back into a useable format.
CDP is not a replacement for all backup operations, since it does not provide long term data retention. Most organisations continue doing tape backups, but no longer need to run them at night – they can be run during normal business hours, copying data directly from the CDP server to tape media so that your production servers are not interrupted. In addition, CDP enables IT to centralise tape operations, removing that burden (and tape drives) from branch offices. Operations improve for both the data centre and remote offices, while providing more reliable data protection and end-user recovery.
iSCSI SAN Enhances Continuous Data Protection
Most CDP products provide protection for application data – file systems, email, and databases – but not for system disks. Advanced SAN-based features such as snapshot and replication technologies are still important for smooth operations – snapshots offer instant recovery from system level catastrophic failures, and remote replication provides fast and easy data restore in case of a site-wide disaster. CDP and advanced SAN features together deliver solid protection and fast recovery for all failure scenarios.
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