Microsoft Word Hardware Reconfiguration Methodology V final2

System and filesystem availability

Depending on the type of data to be restored it may be possible to restore it directly back to the filesystem(s) without interfering with the system’s ongoing operations. However, this will depend greatly on the type of data to be restored. Generally, applications, services, and user data can be restored without ever having to take the system offline. Certain applications or services may require being taken offline temporarily while their data are restored. In addition, depending on the type and amount of user data to be restored it may be necessary for those users to logoff while their data is restored. It is also entirely possible that all the users may have to logoff, depending on how much user data is to be restored and whether it will affect some, most, or all of them. If the backup contains operating system data, however, then it is possible that the system will have to be brought offline in order to conduct a restoration; this too will depend on whether the backup must overwrite system-locked files or other key operating system files that must not be changed while the system is operational. Thus, a determining factor in whether the system or filesystem is to be taken offline will depend greatly on the type of data to be restored.

If a backup was done using DD then the filesystem must be unmounted prior to restoring its data, or it can be mounted using the system’s loopback device feature and mounted as a virtual filesystem and accessed from there. If the data was backed up using Dump then the filesystem can usually remain mounted in so long as the files to be overwritten are not in use. Tar and Cpio- based backups can generally be restored without problem in so long as the files they overwrite are also not in use. In certain cases, an alternative to using another boot device for performing a restoration, the system can be brought into single-user mode and restored from there. However, if the data resides over the network then procedures should exist for how to access the network and data from within single-user mode. In certain cases, where specific files must be restored along with the rest of the restoration that cannot be executed because certain files cannot be overwritten when the system is active, a rescue or Live CD will have to be used. Finally, most restorations can be made to filesystems while they are actively mounted; however, this will depend on both the type of backup and data to be restored.

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