SLAMorris Final Thesis After Corrections.pdf - Cranfield University

then stored and marked as a complete file in the logs. Fragments in this
category would be stored in the H2 directory.
Store Category_2: Fragment is the start of the file
In this case the file would not be resident in the MFT and would be the start of a
larger file; therefore it should begin with the file signature “CMMM” and the valid
header structure identified in Chapter 6. The file header contains the total size
of the file; when divided by the fragment size the number of fragments in the file
can be calculated. After the file header the remainder of the file stores
subrecord chunks; each chunk has a header which contains the total size of the
chunk. Fragments in this category would be stored in the H2 directory.
Store Category_3: Fragment is in the middle of the file
As described in the previous category, these files store information in chunks;
each chunk has a header and a visual thumbnail. Information in the middle of
the file can therefore either contain some information from a subrecord header,
or consist entirely of visual thumbnail data.
If the fragment contains metadata it will have been classified as H2, these
fragments at least part of a structurally valid subrecord header, or a visual
thumbnail file signature. These fragments represent the start and the end of
chunks; they can provide information on the size of the chunks which can be
used to ascertain the number of fragments in the subrecord.
If the fragment contains image-only data it will have been classified as H3; they
are the second part of a subrecord chunk. The visual thumbnail may span over
several fragments, therefore in a file there may be multiple image-only
fragments next to each other.
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