Abstract: Described embodiments provide a method of recovering storage space on a solid state disk (SSD). An index and valid page count are determined for each block of a segment of an SSD. If the valid page count of at least one block in the segment is zero, a quick clean is performed. A quick clean deallocates blocks having zero valid pages and places them in a queue for erasure. Otherwise, a deep clean is performed. A deep clean determines a compaction ratio, N-M, wherein N is a number of partially valid blocks and M is a number of free blocks required to compact the valid data from the N partially valid blocks into M entirely valid blocks. At least one data structure of the SSD is modified to refer to the M entirely valid blocks, and the N partially valid blocks are placed in the queue for erasure.

Abstract: Described embodiments provide a method of recovering storage space on a solid state disk (SSD). An index and valid page count are determined for each block of a segment of an SSD. If the valid page count of at least one block in the segment is zero, a quick clean is performed. A quick clean deallocates blocks having zero valid pages and places them in a queue for erasure. Otherwise, a deep clean is performed. A deep clean determines a compaction ratio, N-M, wherein N is a number of partially valid blocks and M is a number of free blocks required to compact the valid data from the N partially valid blocks into M entirely valid blocks. At least one data structure of the SSD is modified to refer to the M entirely valid blocks, and the N partially valid blocks are placed in the queue for erasure.

Abstract: A method for recovering data from marginally defective data sites on a disk drive surface. If a user data site is determined to be marginally defective during a read operation, a read error recovery procedure is performed on the marginally defective data site. The read error recovery procedure begins by conditionally reassigning data from the marginally defective data site to a spare data site. Next, the data from the marginally defective data site is rewritten to the marginally defective data site. If the data rewrite operation is successful, the method ends. If the data rewrite operation fails, the conditionally reassigned data from the marginally defective data site is reassigned to the spare data site.

Abstract: A method of managing defective data sites on a hard disk drive through a shared defect table. The method writes both skip type entries and vector type entries to the defect table. Skip type entries represent defective data sites that are to be skipped during operation of the disk drive, and vector type entries represent defective data sites which have been reassigned to spare data sites and alternate locations on the disk. Both skip type entries and vector type entries are in a common format within the defect table, where the top two data bits of each entry distinguish skip type entries from vector type entries. The method also manages a separate cross-reference table for vector type entries, where the location of the reassigned defective data site is associated with the location of a spare data site which contains the data from the reassigned site. The shared defect table provides an efficient way for distinguishing skipped and vectored defective data sites during subsequent disk operation.

Abstract: A method for reassigning a defective data site on a disk surface of a disk drive during a write operation. When a write error is detected while writing a data block to a user data site, a write error recovery procedure is performed on the user data site. If the write error recovery procedure determines that the user data site contains an unrecoverable error, the data block is written to a spare data site located at a different area of the disk surface, and a cross-reference entry for the reassignment is stored in memory on the disk drive. Upon completion of the write operation, the user data sites encountering write errors are reassigned to the spare data sites. The reassignment operation includes marking all user data sites encountering write errors as defective data sites, adding all user data sites encountering write errors to a list of defective data sites, and writing the reassignment cross reference entries stored in the disk drive memory to the disk surface.