Endless memory
A storage device includes a controller that is configured to execute safe deletion operations so as to free up storage space on the device in response to triggering events. The safe deletion operations ensure that the data states of a host device making use of the storage device and the storage device itself are synchronized so as to prevent deletion of data from the storage device before it is offloaded to another storage platform.
1. A method of autonomous operation of a storage device controller, comprising: a controller of a storage device determining candidate files for deletion from storage media of the storage device, said storage media communicatively coupled to the controller, and effecting said deletion across a plurality of host device synchronization events, in each instance of a host synchronization event, the controller determining whether activities associated with preparing the candidate files for deletion were impacted so as to require repetition of said activities, and, if so, repeating the activities, otherwise carrying on with deletion of the candidate files, until said candidate files are deleted from the storage media.
2. The method of claim 1 , wherein deletion of the candidate files from the storage media is indicated by sectors of the storage media formerly associated with the candidate files being marked as available to store new data.
3. The method of claim 1 , wherein the controller begins preparations for deleting the candidate files upon recognition of a triggering event comprising one of: an indication that a storage media utilization threshold has been reached or exceeded, a programmed action, or a manual intervention by a user of a host device.
4. The method of claim 1 , wherein the candidate files are included in a group of: oldest files stored in the storage media, least recently accessed files stored in the storage media, or least frequently accessed files stored in the storage media.
5. The method of claim 1 , wherein at least one of the host device synchronization events comprises a power-down-then-power-up cycle of a host device.
6. The method of claim 1 , wherein different ones of the host device synchronization events are distinguished from one another by the controller recognizing a host device access of a file system of the storage device consistent with file system mounting operations.
7. The method of claim 1 , wherein the controller repeats deletion processes for different ones of candidate files until at least one of the following criteria is met: a deletion threshold for the storage device has been reached, a fixed number or percentage of files stored in the storage device have been deleted, or a designated percentage of storage space in the storage device has been made available for storing new files.
8. A storage device comprising a controller communicatively coupled to a host device interface and a storage media, said controller configured to determine candidate files for deletion from storage media of the storage device, and to effect said deletion across a plurality of host device synchronization events, the controller being further configured to determine, in each instance of a host synchronization event, whether activities associated with preparing the candidate files for deletion were impacted so as to require repetition of said activities, and, if so, to repeat the activities, otherwise to carry on with deletion of the candidate files, until said candidate files are deleted from the storage media.
9. The storage device of claim 8 , wherein the storage device comprises a media card and the controller is configured to initiate said deletion upon receipt of a signal from a host digital camera interface.
10. The storage device of claim 8 , wherein the controller is configured to initiate said deletion in response to a triggering event comprising one of: an indication that a storage media utilization threshold has been reached or exceeded, a programmed action, or a manual intervention by a user of a host device.
11. The storage device of claim 8 , wherein the candidate files are included in a group of: oldest files stored in the storage media, least recently accessed files stored in the storage media, or least frequently accessed files stored in the storage media.
12. The storage device of claim 8 , wherein at least one of the host device synchronization events comprises a power-down-then-power-up cycle of a host device.
13. The storage device of claim 8 , wherein different ones of the host device synchronization events are distinguished from one another by the controller recognizing a host device access of a file system of the storage device consistent with file system mounting operations.
14. The storage device of claim 8 , wherein the controller is configured to repeat deletion processes for different ones of candidate files until at least one of the following criteria is met: a deletion threshold for the storage device has been reached, a fixed number or percentage of files stored in the storage device have been deleted, or a designated percentage of storage space in the storage device has been made available for storing new files.
15. A storage device comprising a controller communicatively coupled to a storage media and an interface of a host device, said controller configured to determine candidate files for deletion from the storage media of the storage device, and to effect said deletion across at least one host device synchronization boundary, responsive to a triggering event, wherein said host device synchronization boundary defines states of knowledge of a file system of said storage device, a first of said states being that in which the host device and the controller share a common understanding of said file system and a second in which the host device and the controller do not share said common understanding of said file system.
16. The storage device of claim 15 , wherein the storage device comprises a media card and the controller is configured to initiate said deletion upon receipt of a signal from a host digital camera interface.
17. The storage device of claim 15 , wherein the triggering event comprises one of: an indication that a storage media utilization threshold has been reached or exceeded, a programmed action, or a manual intervention by a user of the host device.
18. The storage device of claim 15 , wherein the candidate files are included in a group of: oldest files stored in the storage media, least recently accessed files stored in the storage media, or least frequently accessed files stored in the storage media.