| Introduction |
There
are a number of NT disk defraggers on the market. These tools are useful
for performing a general defragmentation of disks, but while most files
are defragmented on drives processed by these utilities, some files may
not be. In addition, it is difficult to ensure that particular files
that are frequently used are defragmented - they may remain fragmented
for reasons that are specific to the defragmentation algorithms used by
the defragging product that has been applied. Finally, even if all files
have been defragmented, subsequent changes to critical files could cause
them to become fragmented. Only by running an entire defrag operation
can one hope that they might be defragmented again.
Contig
is a single-file defragmenter that attempts to make files contiguous on
disk. Its perfect for quickly optimizing files that are continuously
becoming fragmented, or that you want to ensure are in as few fragments
as possible. |
| Installation
and Use |
Contig
works on NT 4.0 and higher. Contig can be used to defrag an
existing file, or to create a new file of a specified size and name,
optimizing its placement on disk. To make an existing file contiguous
use Contig as follows:
Usage:
contig [-v] [-q] [-s] [filename]
Use the
-v switch to have Contig print out information about the file
defrag operations that are performed. Use the -s switch to perform a
recursive processing of subdirectories when you specify a filename
with wildcards. For instance, to defragment all DLLs under c:\winnt
you could enter "contig -s c:\winnt\*.dll". The -q switch,
which over-rides the -v switch, makes Contig run in "quiet"
mode, where the only thing it prints during a defrag run is summary
information.
To make
a new file that is defragmented upon creation, use Contig like
this:
Usage:
contig [-v] [-n filename length]
|
| How
It Works |
Contig
uses the native Windows NT defragmentation support that was
introduced with NT 4.0 (see my documentation
of the defrag APIs for more information). It first scans the disk
collecting the locations and sizes of free areas. Then it determines
where the file in question is located. Next, Contig decides
whether the file can be optimized, based on free areas and the number of
fragments the file currently consists of. If the file can be optimized,
it is moved into the free spaces of the disk.
A
significant amount of code is present in Contig to deal with
NTFS files, which can be compressed. In addition, Contig must
only move 16-cluster aligned portions of a NTFS file, and must not move,
in one call to NT's defrag engine, a NTFS file segment that straddles a
256KB boundary in the file. Note
that Contig does not move other files in an effort to make
contiguous space on the disk for the target file.
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