Disk driver cluster management of time shift buffer with file allocation table structure
View Patent ↗A file allocation system for a hard disk drive includes a memory with driver logic and a processor configured with the driver logic to receive a request to allocate hard disk space of a defined size for a buffer file. In some embodiments, the processor is configured with the driver logic to allocate clusters for the buffer file from a plurality of clusters on the hard disk, wherein the clusters for the buffer file store media content instances. In some embodiments, the processor is configured with the driver logic to designate a portion of the clusters of the buffer file for at least one non-buffer file such that the non-buffer file is permitted to share the portion of the clusters of the buffer file with the buffer file.
1. A computer readable storage medium comprising a device driver comprising:
logic configured to allocate clusters on a file allocation table for a buffer file for buffer space on a disk and to cause media content instances to be written to the buffer space;
the file allocation table comprising:
a first data structure comprising file list entries for files, wherein the file list entries include the clusters allocated for each of the files; and
a second data structure comprising cluster list entries for the clusters, wherein the cluster list entries identify the clusters and a quantity of the files that simultaneously share each one of the clusters;
logic configured to limit the buffer file to a substantially constant buffer file size, such that when the buffer file approaches a full status, a cluster storing the oldest media content is first deallocated from the buffer file and a new cluster is correspondingly allocated to the buffer file; and
logic configured to maintain the buffer space as substantially constant in size by autonomously and automatically removing buffer space clusters designated for a permanent recording and replacing the removed buffer space clusters with replacement clusters without intervention or further instruction from the device driver.
2. The computer readable storage medium of claim 1 , wherein the buffer space clusters designated for the permanent recording are permitted to be simultaneously shared among the buffer file and a file for the permanent recording.
3. The computer readable storage medium of claim 2 , wherein the logic is further configured to use a file allocation table.
4. The computer readable storage medium of claim 3 , wherein the file allocation table includes a first data structure comprising a list of the clusters for each of the files, and a second data structure comprising a list of the clusters located on the disk and a file sharing counter of how many of the files share each of the clusters.
5. The computer readable storage medium of claim 4 , wherein the logic is further configured to increment the file sharing counter when the number of the files that are shared are increased and decrement the file sharing counter when the number of the files that are shared are decreased.
6. The computer readable storage medium of claim 2 , wherein the logic is further configured to generate normal play time for each one of the files to track locations in each of the files and to track locations of media content instances.
7. The computer readable storage medium of claim 1 , wherein the logic is further configured to generate normal play time for write operations and read operations to the disk.
8. The computer readable storage medium of claim 1 , wherein the file list entries further include a filename for each of the files and starting and ending sectors of each of the files.
9. The computer readable storage medium of claim 1 , wherein the quantity of the files that share each one of the clusters is tracked in a file sharing counter.
10. The computer readable storage medium of claim 1 , wherein the file sharing counter can have values of zero to signify that a corresponding cluster is available to be written to, values of one to signify that the corresponding cluster is used for a buffer file, and values greater than one to signify that corresponding clusters are to be used for permanent recordings.
11. The computer readable storage medium of claim 1 , wherein the cluster list entries are updated such that a buffer file of clusters is limited to a substantially constant buffer file size, such that when the buffer file approaches a full status, a cluster storing the oldest media content is first deallocated from the buffer file and a new cluster is correspondingly allocated to the buffer file.