Microsoft Word Hardware Reconfiguration Methodology V final2

Filesystem formats

Linux supports multiple filesystems formats and provides the necessary tools for fixing them. However, how well a given tool supports, checks, and fixes one or more filesystem errors will depend largely on the maturity of the tool and its underlying filesystem. All of the major filesystems commonly used by Linux are fully supported. In addition, Linux supports the mounting of loopback virtual filesystems (i.e. DD image files, ISO files, etc.).

7. Bad blocks

Although much attention is paid to the filesystem, it is also important to check a disk drive’s surface for physical errors. Disk drives can suffer from the effects of excessive wear and tear due to the reading and writing of the disk’s heads. This wear and tear can result in the formation of bad blocks. These bad blocks are damaged physical disk sectors that contain actual information; however, that information may or may not be useful just as it may or may not reside on unused disk space. What information is contained within a disk block will depend on where it resides with respect to the underlying filesystem. Although a few bad blocks by themselves will not result in an inconsistent filesystem, they can cause files to be damaged, missing, or corrupt. The Linux operating system provides a tool to check for bad blocks, repair physical errors, and move filesystem data and files to good blocks. The program provided by Linux is the Badblocks disk- checking program.

It is important to perform bad block checking before any errors become disruptive to the operating system or the users. However, bad block checking can only be done on unmounted filesystems, and in the case of the root filesystem, it can only be done from a rescue or Live CD. This can be further complicated by the operational requirements of C2 computer systems. Nevertheless, time should always be made at periodic intervals to perform bad block checking; a good time will be to perform this task when performing other system maintenance-related tasks. However, the type of disk drive used will dictate when and how often checks should be made. Some advanced SCSI disks offer the ability to dynamically check and repair bad blocks as soon as they are found; however, this feature is only available a select few disk drives.

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