A flash memory system is designed to reduce inefficiencies associated with keeping track of logical block address (LBA) to physical block address (PBA) correlation or mappmg—each logical block address generated by a host digital system and associated with data when the data is sent to be stored in the flash memory system by the host digital system. The flash memory system preferably comprises at least one flash memory device having a flash memory array, the flash memory array including a plurality, of blocks for storing data and for storing (LBA to PBA) correlation, each block having a plurality of sectors, and a controller coupled to each flash memory device, the controller including a new space manager. By removing from the space manager the task of tracking correlation between the LBA and the PBA, considerable savings in manufacturing costs and logic circuit area on an integrated circuit are achieved and design flexibility attained. The new space manager continues to keep track of the flags associated with the blocks in the flash memory system. However, sufficient blocks are specifically reserved for keeping track of the (LBA to PBA) correlation of the data stored in the flash memory system and are referred to as correlation blocks. In addition, the flash memory system avoids erase-before-write operations whenever possible during the process of keeping track of (LBA to PBA) correlation.

Flash memory system and method implementing LBA to PBA correlation within flash memory array

A magnetic disk storage system is disclosed wherein byte synchronization to sector data is achieved even when noise in the read channel, due for instance to a thermal asperity (TA), corrupts the primary preamble and/or sync mark fields or causes a loss of frequency or phase lock. The data sector format is modified to comprise at least one secondary sync mark in addition to the conventional primary sync mark recorded at the beginning of the data field. In this manner, when the primary sync mark becomes undetectable due to errors, or when byte synchronization is lost, the storage system can still synchronize to the data sector using the secondary sync mark. The secondary sync mark is preferably spaced apart from the primary sync mark with either a gap (no data) or user data inserted inbetween. In the latter embodiment, two methods are employed to recover user data inbetween the primary and secondary sync marks when the primary sync mark is undetectable: on-the-fly erasure pointer error correction, and buffering to facilitate retroactive synchronization. The secondary sync mark may optionally include a secondary preamble to facilitate phase locking to the data when the primary preamble is corrupted by errors. The present invention also provides "split segment" resynchronization for synchronizing a first section of data using a first mark, and retroactively synchronizing a second section of data using a following sync mark when synchronization is lost.

Thermal asperity compensation using multiple sync marks for retroactive and split segment data synchronization in a magnetic disk storage system

Apparatus and methods are disclosed for providing an improved system for encoding and decoding of Reed-Solomon and related codes. The system employs a k-bit-serial shift register for encoding and residue generation. For decoding, a residue is generated as data is read. Single-burst errors are corrected in real time by a k-bit-serial burst trapping decoder that operates on this residue. Error cases greater than a single burst are corrected with a non-real-time firmware decoder, which retrieves the residue and converts it to a remainder, then converts the remainder to syndromes, and then attempts to compute error locations and values from the syndromes. In the preferred embodiment, a new low-order first, k-bit-serial, finite-field constant multiplier is employed within the burst trapping circuit. Also, code symbol sizes are supported that need not equal the information byte size. The implementor of the methods disclosed may choose time-efficient or space-efficient firmware for multiple-burst correction.

Reed-Solomon code system employing k-bit serial techniques for encoding and burst error trapping

Data objects are sent using a data carousel and forward error correction. This involves segregating a file into groups, wherein each group represents k data blocks. From the k data blocks of each group, n erasure-encoded blocks are calculated, where n>k. The n erasure-encoded blocks are sent in a round-robin fashion using IP multicast technology: the first erasure-encoded block for each group, then the second block of each group, and so on. At a receiver, the blocks are stored on disk as they are received. However, they are segregated by group as they are stored. When reception is complete, each group is read into RAM, decoded, and written back to disk. In another embodiment, the receiver segregates allocated disk space into areas corresponding to sets of groups. Received blocks are then segregated only by set as they are written to disk. One or more RAM buffers can be used in this embodiment. When reception is complete, each set is read into RAM, decoded, and then written back to disk.

Data carousel receiving and caching

When record marks are recorded on a recording medium while making a code symbol "1" of data by obtained coding write information according to a coding system having no DC free property correspond to every edge of the record marks, the recording is effected while inserting resynchronizing signals into the write information with a constant interval. For the resynchronizing signal either one selected between a first resynchronizing code pattern, in which the number of symbols "1" contained therein is even, and a second resynchronizing code pattern, in which the number of symbols "1" is odd, so that an accumulated charge obtained from the run length of the coded data approaches zero is used. Each of the first and the second resynchronizing code pattern contains at least a specified pattern, which doesn't meet the coding rule. The selection is effected by adding a run length switching code to the resynchronizing signal and by switching it to "0" or "1" depending on an output of a run length measuring circuit and a run length judging circuit. In this way it is possible to suppress fluctuations in the level of a reproduced signal obtained from the record marks recorded on the recording medium and to realize a stable data detection by using the original waveform detection method, by which the reproduced signal is converted into a binary signal by using a suitable slice level.

Information recording method and optical disk apparatus using same

A record medium, such as a magnetic tape, optical disk, magnetic disk, and the like stores data signals and error redundancy signals Resynchronization signals are interleaved between the recorded signals such that the error redundancy signals are usable to correct signals recorded between such interposed resynchronization signals wherein no error redundancy signals are recorded Error pointing redundancy signals are recorded between all of the resynchronization signals for pointing to signals in error for enhancing the error correction Such error pointing signals can be cyclic redundancy check (CRC) signals Controls for taking advantage of the above-described arrangement are also described Reframing and clock synchronization controls are also disclosed

Enhanced data formats and machine operations for enabling error correction

A record medium, such as a magnetic tape, optical disk, magnetic disk, and the like stores data signals and error redundancy signals. Re-synchronisation signals are interleaved between the recorded signals such that the error redundancy signals are usable to correct signals recorded between such interposed re-synchronisation signals wherein no error redundancy signals are recorded. Error pointing redundancy signals are recorded between all of the re-synchronisation signals for pointing to signals in error for enhancing the error correction. Such error pointing signals can be cyclic redundancy check (CRC) signals. Controls for taking advantage of the above-described arrangement are also described. Reframing and clock synchronisation controls are also disclosed.

Steven Wayne Roach

Papers

Enhanced data formats and machine operations for enabling error correction

Enhanced error recovery track recording