A method for calculating a plurality (M) of redundancy blocks for multiple (N) data blocks of a plurality (D) of words each, the method comprises: receiving the number (M) of redundancy blocks by a calculator that comprises multiple (R) calculation units; configuring the calculator according to M and R; concurrently calculating, if M equals R, by the multiple (R) calculation units of the calculator, R sets of parity vectors, each set includes a plurality (D) of parity vectors; and calculating the plurality (M) of the redundancy blocks based on the R sets of parity vectors.

Methods, apparatus and computer program products for a distributed system include dividing logical volume data into data subsets, and defining at least one distributedly storage configuration for the logical volume. Metadata for the logical volume is written to a first set of first metadata tables, and the first set of first metadata tables is divided into metadata subsets having a one-to-one correspondence with the data subsets. The metadata subsets are distributed among the multiple digital information devices, and the metadata is copied from the first set of first metadata tables to a second set of corresponding second metadata tables in a one-to-one correspondence with the first metadata tables, and the second metadata tables are distributed among the multiple digital information devices.

In some examples, an erasure code can be implemented to provide for fault-tolerant storage of data. Maximally recoverable cloud codes, resilient cloud codes, and robust product codes are examples of different erasure codes that can be implemented to encode and store data. Implementing different erasure codes and different parameters within each erasure code can involve trade-offs between reliability, redundancy, and locality. In some examples, an erasure code can specify placement of the encoded data on machines that are organized into racks.

For recovering from a RAID array failure in the deduplication repository, creating a new backup volume using a synchronized FC backup of the source production volume residing on an alternative RAID array.

The invention discloses a method and controller for processing data multiplication in a RAID system. Map tables are generated for all values in a field, respectively. The length of an XOR operation unit is chosen to be appropriate w bits (e.g., 32 bits or 64 bits). One or several XOR operation units form a multiplication unit of a data sector. When computing on-line, data in a disk drive of a disk array are performed with XOR operations in accordance with one of the map tables using an XOR operation unit as one unit while computing on the multiplication unit to obtain a product of multiplication. Making use of the RAID system established according to the disclosed method, only XOR operations are required to compute parity data or recover damaged user data. Moreover, several calculations can be performed simultaneously. Therefore, the efficiency of the RAID system can be effectively improved.

Erasure code syndrome computation based on Reed Solomon (RS) operations in a Galois field to permit reconstruction of data of more than 2 failed storage units. Syndrome computation may be performed with coefficient exponents that consist of 1, 0, and 1. A product xD of a syndrome is computed as a left-shift of data byte D, and selective compensation based on the most significant bit of D. A product x.sup.1D of a syndrome is computed as a right-shift of data byte D, and selective compensation based on the most significant bit of D. Compensation may include bit-wise XORing shift results with a constant derived from an irreducible polynomial associated with the Galois field. A set of erasure code syndromes may be computed for each of multiple nested arrays of independent storage units. Data reconstruction includes solving coefficients of the syndromes as a Vandermonde matrix.

A method begins by a dispersed storage (DS) processing detecting unavailability of a storage device of a site of dispersed storage network (DSN) memory to produce an unavailable storage device. The method continues with the DS processing module reassigning a fraction of a logical address sub-range of the unavailable storage device to one or more other storage devices, rebuilding one or more logically addressable data objects to produce one or more rebuilt data objects and storing the one or more rebuilt data objects in the one or more other storage devices. When the unavailable storage device becomes available, the method continues with the DS processing module reallocating the fraction of the logical address sub-range from the one or more other storage devices to the storage device and transferring the one or more rebuilt data objects from the one or more other storage devices to the storage device.

An accelerated erasure coding system includes a processing core for executing computer instructions and accessing data from a main memory, and a non-volatile storage medium for storing the computer instructions. The processing core, storage medium, and computer instructions are configured to implement an erasure coding system, which includes: a data matrix for holding original data in the main memory; a check matrix for holding check data in the main memory; an encoding matrix for holding first factors in the main memory, the first factors being for encoding the original data into the check data; and a thread for executing on the processing core. The thread includes: a parallel multiplier for concurrently multiplying multiple entries of the data matrix by a single entry of the encoding matrix; and a first sequencer for ordering operations through the data matrix and the encoding matrix using the parallel multiplier to generate the check data.

Methods, apparatus and computer program products for a distributed system include dividing logical volume data into data subsets, and defining at least one distributedly storage configuration for the logical volume. Metadata for the logical volume is written to a first set of first metadata tables, and the first set of first metadata tables is divided into metadata subsets having a one-to-one correspondence with the data subsets. The metadata subsets are distributed among the multiple digital information devices, and the metadata is copied from the first set of first metadata tables to a second set of corresponding second metadata tables in a one-to-one correspondence with the first metadata tables.

According to one embodiment, an apparatus comprises one or more memory devices and one or more processors coupled to a circuit board. The memory devices are configured according to a second memory technology. The processors are configured to receive messages conforming to a first memory technology, translate the messages from the first memory technology to the second memory technology, and send the translated messages to the memory devices.