Microsoft Word Hardware Reconfiguration Methodology V final2

Active operating system

A determining factor for selecting the appropriate type of backup scheme will depend on whether the operating system can be left running while backing it up. This will depend on a host of issues such as file types, special file locking mechanisms, and the availability of devices and files. Generally, most if not all operating system files can be backed up while the system is running; however, it may be necessary to shut down certain services and user-based applications before proceeding with a backup. Consider the following:

1. 
   What is the availability of the operating system’s files? Are they all available? Are some unavailable? Can the backup proceed without those files? Generally, once applications and services have been disabled (only if necessary) the only inaccessible files are volatile and device-locked files that are not generally required for operating system backups. However, if one or more of these files must be backed up, then an offline system backup using Dump or DD can be using a rescue or Live CD.
   

2. 
   If necessary, can the operating system be shutdown for a given period to back it up? This may depend on organizational policies and operational requirements. An inactive operating system and its files can always be backed up when it is offline, regardless of file type, data contents, access lists, permissions, etc.
   

3. 
   Can portions (i.e. partitions) of the operating system be taken offline or made read-only in order to decrease backup and system downtime while other online parts are backed up? For example, /usr or /var could be taken offline since few to no operational changes are made here while the system is running.
   

4. 
   Is it important to backup the more volatile portions of the operating system such as /proc? Generally, the answer is no as most of its contents are volatile and dynamic and is only required by the running kernel. Only certain static text configurations are worth backing up from here, but these configurations should always be made from start-up and initialization files and scripts. However, if necessary Dump can often be used for backing up the contents of /proc without taking the system offline.
   

5. 
   If certain files cannot be backed up while the system is online will a restoration be successful without those files? If not, are there are other available sources for those files? If not, then the operating system will have to be taken offline in order to backup those files.
   

6. 
   Is the operating system spread across multiple disks and/or partitions? If so, then often these operating systems are easier to backup than single-partition systems. There are many various reasons why this type of system is easier to backup. Dump can be used for almost all the partitions and where it cannot be used, if a given partition can be brought offline or is inactive, and then DD can be used.
   

7. 
   Many other factors exist that must be contended with that go beyond the scope of this subsection. Whenever system volatility and file accessibility-based issues are present, backup procedures will generally be more cumbersome than they would otherwise have
   

been. Thus, there is unfortunately no ubiquitous solution for operating system backups, only practical solutions.

9.