There are several possible backup, recovery, and restore strategies in general use for Internet data center servers. At one end of the spectrum is total backup of all hard disk content on the server. Then there are many flavors of backups that target specific subsets of the hard disk data. Taking a front-end Web server as an example, one could back up only the custom Web content files and, within that, perform full weekly backups followed by daily incremental backups.
However, recommends that the general backup performed for all solution servers be a full and complete backup of the entire hard disk system. Although this might seem extreme, you should review the following sections to learn why this is advocated.
Costs of the Complete Backup Strategy
There are increased costs associated with performing full backups every time versus backups that target only content or a similar subset of persistent data. The two obvious costs are media and time. It takes more media to perform a complete backup, because part of the backup set is constant. The operating system, application files, and other installed software already exists on other media (the installation media), and is identical on many servers. In general, this subset of a complete backup is utterly redundant - the bits will not get lost if this data is not part of a backup/restoration/recovery (BRR) plan.
Advantages of the Complete Backup Strategy
The restoration process using backups made with the Microsoft Windows Server 2003 Backup Utility requires the installation of the Windows Server 2003 operating system followed by recovery from the backups. Most restorations follow this sequence, though there are some that do not require an operating system installation first, relying on the installation of a kernel application that then restores the hard disks, including the operating system bits. In either case, a recovery process involving anything less than a complete and total backup requires one or more of the following:
- Installation of the operating system or of a kernel that can
restore the backup images.
- Restoration of the system state of the operating
- Installation of all other applications not included in the
- Installation of all application and operating system updates
and service packs.
- Recovery of data of numerous types (Web content, databases, and
other application data), application data stores, configuration
files, and so on.
Furthermore, any BRR plan that does not rely on complete backups requires you to first restore each of these categories from the most current complete backup and then restore each incremental backup made since that date.
Contrast this to the recovery process based on a complete backup:
- Installation of the operating system.
- Restoration of the current complete backup.