Preparing to recover from problems

``Summary of system administration tasks'' describes a number of practices that can help you avoid system problems and minimize the impact of system failures that happen. A few of these points are summarized here:

• Make an emergency boot floppy disk set as discussed in UNRESOLVED XREF-0. If the root filesystem or a critical booting file are corrupted by a system crash, the emergency boot floppy disk set can be used to recover the system. Otherwise, you may need to reinstall the software before you will be able to boot the system.

• Record your root disk information as described in ``Recording your root disk layout''. This information is vital for restoring your system after a root disk failure.

• Monitor system performance, error logs, and the system log book regularly. This can enable you to correct problems before they cause a hard failure. See ``Checking system files with error histories'' for a list of useful error log files.

• Install an uninterruptible power supply (UPS) on the system to protect the system from damage during power surges and failures.

• Back up the system regularly. Consider running full system backups every week or two. Because incremental backups are usually faster than full backups, it is tempting to run full backups only rarely. However, if you need to restore files, you may need to restore the most recent full backup plus all incrementals run since then, which could be a long and tedious process.
  

• Understand the purpose of the ``override'' terminal in dealing with the security subsystem. The override terminal is used to correct errors that prevent access to other terminals. By default, the console multiscreen (/dev/tty01) is the override terminal. For more information, see ``Starting and stopping the system''.