Microsoft Word Hardware Reconfiguration Methodology V final2

Repairs

The Linux operating system supports and provides all of the necessary tools for checking and repairing a variety of filesystem formats and all but the most troublesome errors can be found and fixed. It provides the Fsck utility for performing filesystem reparation. Although filesystem checking is important, there are certain dos and don’ts. The most important don’t is that a filesystem should never be repaired when it is mounted, even if it is mounted in read-only mode. Even when a read-only filesystem is mounted, buffered changes made to it are likely to result in a more serious problem than that which was fixed if the disk is remounted as read/write. Filesystems can be checked (but not repaired) when they are mounted; however, this can be dangerous, depending on the filesystem type and the level of disk or partition activity and underlying damage. It is always safest to check a filesystem when it is mounted read-only and it is always safest to repair a filesystem when it is offline. DD image files can also be checked and repaired just as with any other valid partition or filesystem and the same basic rules about checking and repairing apply. Severely damaged filesystems (if a backup is not available) may require forensic tool recovery to reconstruct damaged data and/or filesystem structures. Finally, the root filesystem should always be checked and repaired in single-user mode (during system start-up) or from a rescue or Live CD. Under no circumstances should the root filesystem be repaired while the operating system is active and operational.

5. Scheduling

It is important that time be made periodically for checking a system’s filesystem(s); often the best time to do this is at system start-up. However, some systems, particularly mission critical C2 systems may have operational requirements that make taking them offline difficult. Nevertheless, periodic maintenance is required even on these systems. If time cannot be periodically scheduled for certain systems then filesystem checks and repairs should be made before performing other system maintenance tasks such as updating, upgrading, and/or replacing/adding hardware. Although certain filesystem formats are almost “impossible” to corrupt (i.e. XFS) due to the many inherent safeguards they incorporate they should still be checked as there is no such thing

as a perfectly stable filesystem since they are always changing and in a constant state of flux. In addition, if it is not already done, it is important to incorporate filesystem checking into organizational policy regarding system maintenance. Finally, it is better to have certain systems or services unavailable for brief periods rather than have an inconsistent or corrupt backup or restoration when it really matters.

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