| 摘要 |
Sector and block layers for a database management system improve the integrity of data in a flash memory in view of possible data corruptions caused by power interruptions. The sector layer implements a reclaiming function for copying valid data from a source to a destination so that the source sector can be erased. A sector state register indicates whether a sector is in use, in a first reclaiming state, in a second reclaiming state or in a reclaimed state. A destination sector register for a reclaiming source points to a reclaiming destination. A limitation is placed on permissible reclaiming sources for a given reclaiming destination, so that, if a first sector is a permissible source for a second sector, then the second sector cannot be a permissible source for the first sector. On power up, the sector layer is able to determine if a reclaiming operation was in progress when power was interrupted and, if so, which sectors were the source and destination, and at what point the reclaiming operation must be resumed to complete the operation successfully. At the block layer, a block state register indicates whether a data block is in an erased state, a written state, a committed state, a freed state, a freed and committed state, or a dirty state, a block label register is used to determine whether multiple blocks contain different versions of the same data item, and a block version register indicates which of multiple versions of the same data item were written more recently. On power up, data blocks that may have corrupted data from the prior power interruption are marked as dirty or invalid, and a block-level commit function is performed, in case such an operation was interrupted during the prior power interruption.
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