Windows sysinternals

342 Part II Usage Guide
FIGURE 12-7 DiskView File Errors dialog box.
Each cell in the upper graph represents a volume cluster. (The default cluster size on NTFS
volumes of 2 GB or more is 4096 bytes.) Clicking the Zoom up-arrow increases the cells’ size,
which makes it easier to distinguish individual clusters and to click on a specific cell. If you
scroll to the top of the upper graph, the top row represents the first clusters on the disk, with
cluster number zero represented in the upper left cell, and cluster 1 to its right. The second
row represents the next set of clusters, and so on.
The default color coding in the upper graph shows the arrangement of files on the disk. A
dark blue cell indicates the first of a set of clusters associated with a file, with the subsequent
blue cells representing the clusters of the file that are contiguous with the first one. A red
cell indicates the start of a file’s second or later fragment, with the subsequent blue cells
representing the other clusters in that fragment.
If you deselect Show Fragment Boundaries from the Options menu, these first-cluster
markers are not displayed, and fragment cells show entirely in red. Although this is how
defragmenters have historically displayed file fragmentation, it is an overly pessimistic
view. Indeed, the defragmentation algorithm in Windows 7 does not attempt to coalesce
fragments that are over 64 MB, because the benefits become insignificant while the costs of
moving the fragment data increase.
If you click on a colored cell in the upper graph, DiskView displays the name of the file
occupying that cluster in the text area at the top of the DiskView window and highlights
all clusters belonging to the same file in yellow. Double-click the cell to display the Cluster
Properties dialog box. In addition to showing the selected disk cluster number and the name
of the file occupying that cluster, this lists the file fragments showing contiguous cluster
numbers relative to the file, with file cluster 0 being the first cluster in the file, and the
corresponding disk cluster numbers. In the example shown in Figure 12-8, the file occupies
568 clusters, of which the selected cluster is the 114 th .
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