FAT directory structure for use in transaction safe file system

A system comprising:

• a first file allocation table adapted to define a sequence of data storage clusters;
• a plurality of directories, each of said directories comprising at least two data clusters:
• a first cluster having no transaction-safe data and at least one remaining data cluster comprising transaction-safe data;
• a second file allocation table being a synchronized copy of said first file allocation table;
• a first bitmap image having at least one bit allocated for each of said data storage clusters;
• a second bitmap image being synchronized with said first bitmap image;
• a pointer to a last known good file allocation table, said pointer being further adapted to point to a last known good bitmap image;
• and
• a processor adapted to modify one or more of said directories by a method comprising:
• making a change to said transaction-safe data of said at least one remaining data cluster using said first cluster;
• updating said second file allocation table to reflect said change by modifying said second file allocation table to reference said first cluster while retaining a placeholder cluster in said second file allocation table as a starting cluster, said placeholder cluster referencing a next data cluster in said sequence of data storage clusters that comprises transaction-safe data;
• updating said second bitmap image to reflect said change;
• after completing said change, setting said pointer to said second file allocation table and said second bitmap image;
• synchronizing said first file allocation table to said second file allocation table;
• and
• synchronizing said first bitmap image to said second bitmap image.

A system comprising:

• a first file allocation table adapted to define a sequence of data storage clusters;
• a plurality of directories, each of said directories comprising at least two data clusters:
• a first cluster having no transaction-safe data and at least one remaining data cluster comprising transaction-safe data;
• a second file allocation table being a synchronized copy of said first file allocation table;
• a first bitmap image having at least one bit allocated for each of said data storage clusters;
• a second bitmap image being synchronized with said first bitmap image;
• a pointer to a last known good file allocation table, said pointer being further adapted to point to a last known good bitmap image;
• and
• a processor adapted to modify one or more of said directories by a method comprising:
• setting said pointer to said first file allocation and said first bitmap image;
• making a change to said transaction-safe data of said at least one remaining data cluster using said first cluster;
• modifying said second file allocation table to reference said first cluster while retaining a placeholder cluster in said second file allocation table as a starting cluster, said placeholder cluster referencing a next data cluster in said sequence that comprises transaction-safe data;
• updating said first file allocation table to reflect said change by synchronizing to said second file allocation table;
• and
• updating said first bitmap image to reflect said change.

A method comprising:

• storing a directory in a file system on a computing device by creating a first cluster having no transaction-safe data and a subsequent second cluster comprising transaction-safe data;
• storing a first address for said second cluster in a first file allocation table that defines a placeholder cluster as a starting cluster in a sequence of data clusters for said directory, said placeholder cluster referencing said first address as a next data cluster in said sequence of data clusters for said directory;
• synchronizing said first file allocation table with a second file allocation table;
• toggling a pointer to indicate that said first file allocation table is a known good file allocation table;
• making a change to said transaction-safe data using said first cluster of said directory;
• updating said second file allocation table to reflect said change by modifying said second file allocation table to reference said first cluster of said directory while retaining said placeholder cluster in said second file allocation table as said starting cluster in said sequence of data clusters for said directory;
• after completing said change, setting said pointer to said second file allocation table;
• and
• synchronizing said first file allocation table to said second file allocation table.

A method comprising:

• storing a directory in a file system on a computing device by creating a first cluster having no transaction-safe data and a subsequent second cluster comprising transaction-safe data;
• storing a first address for said second cluster in a first file allocation table that defines a sequence of data storage clusters, said first address being stored in a location for said first cluster;
• defining a first bitmap image having at least one bit assigned for each data storage cluster within said file system;
• synchronizing said first file allocation table with a second file allocation table;
• synchronizing a second bitmap image with said first bitmap image;
• toggling a pointer to indicate that said first file allocation table is a known good file allocation table, said pointer being further adapted to point to a last known good bitmap image;
• making a change to said transaction-safe data using said first cluster;
• updating said second file allocation table to reflect said change by modifying said second file allocation table to reference said first cluster while retaining a placeholder cluster in said second file allocation table, said placeholder cluster referencing said first address as a next data cluster in said sequence of data storage clusters;
• updating said second bitmap image to reflect said change;
• after completing said change, setting said pointer to said second file allocation table and said second bitmap image;
• synchronizing said first file allocation table to said second file allocation table;
• and
• synchronizing said first bitmap image to said second bitmap image.

A method comprising:

• storing a directory in a file system on a computing device by creating a first cluster having no transaction-safe data and a subsequent second cluster comprising transaction-safe data;
• storing a first address for said subsequent second cluster in a first file allocation table that defines a placeholder cluster as a starting cluster in a sequence of data clusters for said directory, said placeholder cluster referencing said first address as a next data cluster in said sequence of data clusters for said directory;
• synchronizing said first file allocation table with a second file allocation table;
• setting a pointer to indicate that said first file allocation table is a last known good file allocation table;
• updating said second cluster by creating a third cluster having a second address;
• updating said first address referenced by said placeholder in said second file allocation table to said second address while retaining said placeholder cluster in said second file allocation table as said starting cluster in said sequence of data clusters for said directory;
• toggling said pointer to indicate said second file allocation table is a last known good file allocation table;
• and
• updating said first file allocation table to said second file allocation table.

A method comprising:

• storing a directory in a file system on a computing device by creating a first cluster having no transaction-safe data and a subsequent second cluster comprising transaction-safe data;
• storing a first address for said subsequent second cluster in a first file allocation table, said first address being stored in a location for said first cluster;
• synchronizing said first file allocation table with a second file allocation table;
• defining a first bitmap image having at least one bit assigned for each data storage cluster within said file system;
• synchronizing a second bitmap image with said first bitmap image;
• setting a pointer to indicate that said first file allocation table is a last known good file allocation table, said pointer being further adapted to point to a last known good bitmap image;
• updating said second cluster by creating a third cluster having a second address;
• updating said first address in said second file allocation table to said second address;
• changing said second bitmap image to indicate said third cluster is used;
• changing said second bitmap image to indicate said subsequent cluster is not used;
• toggling said pointer to indicate said second file allocation table is a last known good file allocation table;
• setting said pointer to further indicate said second bitmap image is last known good;
• updating said first file allocation table to said second file allocation table;
• and
• synchronizing said first bitmap image to said second bitmap image.