Administrator > Backup and Recovery

Why File-based System Backup is a Good Bet

The evolution of file-based, full-system backups

File-based backups used for system recovery have been around for years. And, until recently, file-based meant a long, painstaking, manual process capable of turning off even the most meticulous system administrator.

Image-based backups seemed to solve this problem by eliminating the need to deal with recreating partitions, filesystems, volume groups or other details related to the system’s storage configuration. In an image-based restore, the storage configuration and data from the original system are restored as a whole to the new system. While this method produced fast recovery times, Linux administrators began to realize disk image backup was more of an alternative method with its own set of problems and limitations than an answer to the challenges of manual, file-based backup.

Limitations to Disk Image Backup

Since disk image backups make no distinction between files and instead backup the hard drive as a group of sectors, bare-metal recovery can be quick and easy by simply rewriting a duplicate image onto a new, identical disk drive. This is a fine solution, as long as the old and new systems are indeed identical in type, size, and location—basically the exact same hardware. Any differences in hardware, however, could render an image backup unusable.

Many system administrators know first-hand the frustration caused by the inflexibility of image-based backup. Even more advanced disk image backup products that offer alterations to disk partition tables still fail to understand more advanced and increasingly common storage configuration tools such as the Logical Volume Manager (LVM) or Software RAID (meta-disks) that also must be altered to match new hard disk configuration before data can be restored. In these cases, users must manually alter and build the configuration, usually through command-line utilities and manual editing of configuration files. This also requires users to have knowledge on how to make a system bootable. Rebuilding a system using a disk-image backup requires experienced Linux administrators and could take days, weeks or longer resulting in crippling downtime for an organization.

Advances in File-based Backup

File-based backup tools today can automate the process of recording every aspect of a system separately such as disk, filesystem and boot-loader configuration while supporting all popular Linux storage configuration tools such as LVM and Software RAID. This detailed backup information is used to greatly simplify the recovery of a failed system from scratch, even if hardware differences are detected on the new system. Furthermore, systems rebuilt from the ground up using file-based backups often times operate better than the original because there is virtually no fragmentation when the restore is completed.

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