CompTIA A+ Certification All-in-One Exam Guide

addressing. A block is one step above the physical layout of the drive, which
gives a lot of flexibility in the media. Microsoft continues to use the term
cluster to refer to locations in their file allocation tables. With NTFS, a
cluster and a block are pretty much the same thing, a 4-KB chunk of a drive
(until you get partitions larger than 16 TB). The official term for a cluster is
an allocation unit. You’ll see all three terms used interchangeably in the field.
Maintenance
Hard drive maintenance can be broken down into two distinct functions:
checking the disk occasionally for failed blocks, and keeping data organized
on the drive so it can be accessed quickly.
Error Checking
Individual blocks on hard drives sometimes go bad. There’s nothing you can
do to prevent this from happening, so it’s important that you check
occasionally for bad blocks on drives. The tools used to perform this
checking are generically called error-checking utilities, although the term for
an older Microsoft tool—chkdsk (pronounced “checkdisk”)—is often used.
Chkdsk is a command-line utility. Microsoft called the graphical tool Errorchecking
in Windows 7. Windows 8 and later drop the hyphen, so Error
checking is the current name. macOS uses the Disk Utility. Linux offers a
command-line tool called fsck. Whatever the name of the utility, each does
the same job: when the tool finds bad blocks, it puts the electronic equivalent
of orange cones (placing 0000FFF7 in the FAT/MFT) around them so the
system won’t try to place data in those bad blocks.
EXAM TIP The CompTIA A+ exam objectives mention chkdsk
specifically, but not Error checking. Even without the shout out in the
objectives, expect a question on disk maintenance that refers to Error
checking.
Most error-checking tools do far more than just check for bad blocks.