Abstract: Systems, apparatuses, methods, and computer program products are provided for managing geographically distributed data storage in a group-based communication system and for servicing deletion requests related thereto. In some embodiments, an apparatus physically located in a first geographic area defined by a first geographic boundary is provided. In embodiments, upon determining that an entity identifier associated with a message is associated with a geographic data storage policy, the apparatus is configured to transmit a geographic data residency message package comprising message data of the message to a geographic data residency server physically located within a second geographic area defined by a second geographic boundary. The second geographic area is associated with the geographic data storage policy. In some embodiments, the apparatus is configured to update the message data of the message with residency token data received from the geographic data residency server.

Abstract: A sign bit of a low-density parity-check (LDPC) codeword associated with a translation unit (TU) can be generated by performing an XOR operation on a RAIN drop corresponding to the TU and a raw read of the TU. The LDPC codeword can include a hard bit and three soft bits that include the sign bit. The LDPC codeword can be decoded using the hard bit and the three soft bits. A read recovery operation can be performed on the TU using the decoded LDPC codeword.

Abstract: A memory system includes a plurality of non-volatile memory chips and a controller configured to communicate with a host and control the plurality of non-volatile memory chips. The controller is configured to write a data frame that includes write data and a first parity for error detection and correction of the write data into first memory chips of the non-volatile memory chips in a distributed manner. The first memory chips includes N (N is a natural number of two or more) memory chips. The controller is configured to write a second parity for restoring data stored in one of the N first memory chips using data read from the other N?1 of the N first memory chips, into a second memory chip of the non-volatile memory chips that is different from any of the first memory chips.

Abstract: Continuous value data redundancy, including: receiving, by a storage system, a dataset; determining, based on a data resiliency metric, an integer redundancy value for the dataset from among a plurality of redundancy values; and generating, based on the integer redundancy value for the dataset, data recovery information for the dataset, wherein the integer redundancy value for the dataset is different from at least one other integer redundancy value for another dataset stored within the storage system.

Abstract: Techniques for storage management involve determining, in response to a detection that a disk changes from an unavailable state to an available state, at least one candidate storage unit associated with the disk; acquiring historical access information about the at least one candidate storage unit, the historical information comprising information related to a write request directed to the at least one candidate storage unit when the disk is in the unavailable state; determining a target storage unit from the at least one candidate storage unit based on the historical access information; and rebuilding the target storage unit. Such techniques may, in a low-cost manner, improve rebuilding efficiency and reliability of a storage system.

Abstract: The rate at which reads on a target memory portion initiate error recovery procedures can be monitored in real-time. Trigger rates can be used to perform analysis of a memory sub-system or to implement improvements in the memory sub-system. Trigger rate monitoring can include accessing a count of error recovery initializations for a target memory portion, wherein the count of error recovery initializations corresponds to a number of times a first stage of a multi-stage error recovery process was performed. Trigger rate monitoring can further include accessing a count of read operations corresponding to the target memory portion. The count of error recovery initializations and the count of read operations can be used to compute a trigger rate. The trigger rate, or multiple trigger rates from various times or from various target memory portions, can be used to compute a metric for the memory portion(s).

Abstract: Systems and methods are disclosed, including maintaining an error recovery data structure for a set of codewords (CWs) in a storage system, the error recovery data structure storing indications that specific CWs are correctable or not correctable by specific error handing (EH) steps of a set of multiple EH steps, and determine an order of EH steps for the storage system based on the error recovery data structure. Maintaining the error recovery data structure can include determining if each CW of the set of CWs is correctable by a specific EH step, storing indications of CWs determined correctable by the specific EH step in the error recovery data structure, and, in response to determining that one or more CW in the set of CWs are not indicated as correctable in the error recovery data structure, incrementing the specific EH step.

Abstract: Devices are often connected to a network to facilitate remote interactions with the device. However, such connections may be absent or disabled. However, by utilizing a second device, such as a mobile phone, a transaction may be initiated on a remote device and handed-off to the second device to obtain absent information and complete the transaction. Completion of the transaction may be due to absent data, such as a data that provides absent information or resolves conflicting information in the dataset. The device may communicate with the second device via radio frequency communications and/or other forms of communication (e.g., visually, audibly, etc.), such that information the absent information is obtained and the instructions executed to complete the transaction.

Abstract: A method and apparatus for operating a solid state drive is disclosed comprising receiving at least two commands from a host requiring an action by the solid state drive in a preliminary order, ordering the at least two commands based upon a quality of service classification for the at least two commands to a final order and executing the at least two commands on the solid state drive in the final order, wherein an operational parameter of the solid state drive is modified by at least one of the at least two commands.

Abstract: Techniques for data recovery involve: reading target data corresponding to a first logical block from a first data block of a stripe of a RAID system, the target data being a compressed version of data in the first logical block; in accordance with a determination that an error occurs in the target data, reading data from a plurality of second data blocks of the stripe and first parity information from a first parity block of the stripe; comparing respective checksums of the data read from the plurality of second data blocks with a first predetermined checksum and a checksum of the first parity information with a second predetermined checksum; and determining recoverability of the target data based on a result of the comparison. Accordingly, it is possible to simplify the data recovery process, reduce the calculation and time costs in the data recovery, and improve the data recovery efficiency.

Abstract: A failure estimation support device 2 includes: a first calculation unit 21 configured to calculate single failure occurrence probabilities of individual single rules for each single rule relating to a single failure from past failure occurrence data; a second calculation unit 22 configured to calculate multiple failure occurrence probabilities that multiple failures occur in association for each combination of multiple single rules using the single failure occurrence probabilities; and a correlation rule generation unit 23 configured to select the combination of the multiple failure occurrence probabilities greater than a predetermined threshold among the multiple failure occurrence probabilities as a correlation rule, and the correlation rule is used as training data for making a learned model which estimates a failure factor perform machine learning together with the single rule.

Abstract: Embodiments relate to the field of storage technologies. The method is applied to a flash device whose first physical storage space stores a data block at a first security level and a data block at a second security level and whose second physical storage space stores a data block at a second security level. The method includes: receiving a data write request used to request to write target data, and obtaining a security level of the target data; and writing the target data into the first physical storage space if the security level of the target data is the first security level; or writing the target data into the second physical storage space or writing the target data into the second physical storage space and the first physical storage space if the security level of the target data is the second security level.

Abstract: An example method may include identifying, in a plurality of blocks of data, one or more unallocated blocks, wherein the plurality of blocks further comprises one or more allocated blocks, generating a plurality of checksums, wherein each checksum corresponds to one of the blocks, and the checksums comprise a plurality of first checksums and a plurality of second checksums, wherein each of the first checksums corresponds to one of the unallocated blocks and comprises a predetermined checksum of a block of zeros, and wherein each of the second checksums corresponds to one of the allocated blocks and comprises a checksum of the corresponding one of the allocated blocks, and generating a result checksum in view of the plurality of checksums.

Abstract: A plurality of computing devices are communicatively coupled to each other via a network, and each of the plurality of computing devices is operably coupled to one or more of a plurality of storage devices. One or more of the computing devices and/or the storage devices may be used to rebuild data that may be lost due to a power failure.

Abstract: A memory controller includes a memory interface and a processor. The processor is coupled to the memory interface and controls access operation of a memory device via the memory interface. The processor maintains a predetermined table according to write operation of a first memory block of the memory device and performs data protection in response to the write operation. When performing the data protection, the processor determines whether memory space damage has occurred in the first memory block. When it is determined that memory space damage has occurred in the first memory block, the processor traces back one or more data sources of data written in the first memory block according to the predetermined table to obtain address information of one or more source memory blocks and performs a data recovery operation according to the address information of the one or more source memory blocks.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for maintaining fault tolerance for new writes in a storage system when one or more components of the storage system are unavailable. One of the methods includes determining that one or more first disks of a capacity object of a storage system are unavailable, wherein the storage system comprises a segment usage table identifying the plurality of segments of the capacity object; in response: identifying a plurality of available second disks, adding a plurality of new segments corresponding to the second disks to the capacity object, and adding data identifying the plurality of new segments to the segment usage table; and for each of one or more new write requests to the capacity object: identifying an available segment from the plurality of new segments, and writing data associated with the new write request to the identified available segment.

Abstract: An apparatus comprising a processing device is configured to communicate with a storage node of a storage system via at least one network and to communicate with a compute node that implements at least a portion of an application via the at least one network. The at least one processing device is configured to obtain an input-output request associated with the application from the compute node via the at least one network and to associate information corresponding to the compute node with the input-output request. The at least one processing device is further configured to submit the input-output request and the associated information that corresponds to the compute node to the storage node. The storage node is configured to submit a response to the input-output request to the compute node via the at least one network based at least in part on the information.

Abstract: Systems and methods for dynamic and adaptive interrupt coalescing are disclosed. NVM Express (NVMe) implements a paired submission queue and completion queue mechanism, with host software on the host device placing commands into the submission queue. The memory device notifies the host device, via an interrupt, of entries on the completion queue. Responsive to receiving the interrupt, the host device access the completion queue to access entries placed by the memory device therein. The host device may take a certain amount of time to service the interrupt resulting in host latency. Given knowledge of the host latency, the memory device time the sending of the interrupt so that, given the host latency, the memory device may post the entry to the completion queue in a timely manner.

Abstract: Methods, systems, and devices for error caching techniques for improved error correction in a memory device are described. An apparatus, such as a memory device, may use an error cache to store indications of memory cells identified as defective and may augment an error correction procedure using the stored indications. If one or more errors are detected in data read from the memory array, the apparatus may check the error cache, and if a bit of the data is indicated as being associated with a defective cell, the bit may be inverted. After such inversion, the data may be checked for errors again. If the inversion corrects an error, the resulting data may be error-free or may include a reduced quantity of errors that may be correctable using an error correction scheme.

Abstract: In some examples, a computer system may receive a data object including object data. For example, the system may be one of three or more systems and each system may be located at a different respective geographic location. The system may determine a value representative of the object data content. The system may further determine a plurality of chunks by dividing the object data into a plurality of data chunks based on a total number of the systems and determining a parity chunk for the plurality of data chunks. The system may determine a respective role value corresponding to each of the systems, and may send individual ones of the chunks to respective ones of the systems based on the role value and the value representative of the object data content. In some examples, each system may perform data deduplication independently of the other systems based on received chunks.

Abstract: Embodiments of the present disclosure provide a method, a device and a computer program product for managing a storage system. A method of managing a storage system comprises: determining whether a response time of a file system operation occurring in the storage system exceeds a first predetermined threshold, wherein the storage system comprises at least a memory and a plurality of storage devices and wherein the file system operation synchronizes data stored in the memory to at least one storage device from the plurality of storage devices. The method comprises: in response to the response time exceeding the first predetermined threshold, obtaining trace information related to the file system operation. In addition, the method further comprises determining, by analyzing the trace information, one or more factors that cause timeout of the file system operation.

Abstract: A technique balances data storage activity within a mapped-RAID environment. The technique involves selecting, by processing circuitry, a source slice of storage from multiple slices of storage of the mapped-RAID environment, the source slice containing particular data to be relocated. The technique further involves selecting, by the processing circuitry, a destination slice of storage from the multiple slices of storage of the mapped-RAID environment. The technique further involves relocating, by the processing circuitry, the particular data from the source slice to the destination slice to balance data storage activity within the mapped-RAID environment. The mapped-RAID environment includes multiple storage devices. Each storage device provides multiple non-overlapping device extents.

Abstract: Higher-level redundancy information computation enables a Solid-State Disk (SSD) controller to provide higher-level redundancy capabilities to maintain reliable operation in a context of failures of non-volatile (e.g. flash) memory elements during operation of an SSD implemented in part by the controller. For example, a first computation is an XOR, and a second computation is a weighted-sum. Various amounts of storage are dedicated to storing the higher-level redundancy information, such as amounts equivalent to an integer multiple of flash die (e.g. one, two, or three entire flash die), and such as amounts equivalent to a fraction of a single flash die (e.g. one-half or one-fourth of a single flash die).

Abstract: One embodiment facilitates flash storage management. During operation, the system receives a request to write data to a non-volatile memory. The system writes, in a buffer in association with a controller, the data to a next available portion of a current physical page in a page stripe, wherein the page stripe includes physical pages which each correspond to a sequentially ordered die of the non-volatile memory. The system provides power-loss protection to the current physical page and a second physical page which indicates parity information for the page stripe, thereby providing power-loss protection to an increased number of partially full page stripes.

Abstract: Techniques for rebuilding a failed drive of a plurality of drives are provided. The techniques include: (a) determining a number of empty data stripes that have been allocated from the plurality of drives; (b) applying a set of decision criteria to the determined number to yield a decision, wherein applying the set of decision criteria yields a first decision at a first time and a differing second decision at a second time; (c) in response to the first decision at the first time, deallocating an empty data stripe that was allocated from the plurality of drives to yield a plurality of data extents on disparate drives of the plurality of drives and continuing to rebuild the failed drive onto at least one of the plurality of data extents; and (d) in response to the second decision at the second time, pausing rebuilding the failed drive until applying the set of decision criteria yields the first decision.

Abstract: A first data location is identified, where the first data location is predetermined to store a first parity data based on a plurality of user data at a plurality of data locations of a storage system. A set of user data is stored at a subset of data locations of the plurality of data locations. A second parity data is stored at a memory buffer location. The second parity data is generated based on the set of user data. An indication of an occurrence of an event is received, the event associated with the storage system. In response to receiving the indication of the occurrence of the event, the second parity data is stored at a second data location external to the plurality of data locations. Upon restart of the storage system, the second parity data is transferred to a third data location of the plurality of data locations. The third data location is situated after the subset of the plurality of data locations and prior to the first data location.

Abstract: Mapped RAID protection is provided for data written into multiple logical RAID spaces, and the data written to each one of the RAID spaces is stored in data storage drives contained in a corresponding one of multiple protection groups of data storage drives. Drive health information is collected for each data storage drive contained in the protection groups, and a faultiness level of each individual data storage drive in the protection groups is calculated based on the drive health information. A faultiness-balanced distribution of the data storage drives across the protection groups is then generated based on the calculated faultiness levels of the individual data storage drives.

Abstract: A processor includes at least one memory controller, and a decode unit to decode a persistent commit demarcate instruction. The persistent commit demarcate instruction is to indicate a destination storage location. The processor also includes an execution unit coupled with the decode unit and the at least one memory controller. The execution unit, in response to the persistent commit demarcate instruction, is to store a demarcation value in the destination storage location. The demarcation value may demarcate at least all first store to persistent memory operations that are to have been accepted to memory when the persistent commit demarcate instruction is performed, but which are not necessarily to have been stored persistently, from at least all second store to persistent memory operations that are not yet to have been accepted to memory when the persistent commit demarcate instruction is performed.

Abstract: Methods and systems for rebuilding a failed storage device in a data storage system. For example, a method including identifying a first garbage collection group (GCG) in a storage array for garbage collection; extracting valid data and redundancy information from functioning storage devices in the storage array associated with the first GCG; reconstructing data of a failed storage device associated with the first GCG based on the extracted valid data and redundancy information from the functioning storage devices associated with the first GCG; consolidating the extracted valid data from the functioning storage devices and the reconstructed data of the failed storage device associated with the first GCG; writing the consolidated extracted valid data from the functioning storage devices and the reconstructed data of the failed storage device associated with the first GCG to a second GCG in the storage array; and reclaiming the first GCG identified for garbage collection.

Abstract: Embodiments of the present invention provide systems and methods for recovering a high availability storage system. The storage system includes a first layer and a second layer, each layer including a controller board, a router board, and storage elements. When a component of a layer fails, the storage system continues to function in the presence of a single failure of any component, up to two storage element failures in either layer, or a single power supply failure. While a component is down, the storage system will run in a degraded mode. The passive zone is not serving input/output requests, but is continuously updating its state in dynamic random access memory to enable failover within a short period of time using the layer that is fully operational. When the issue with the failed zone is corrected, a failback procedure brings the system back to a normal operating state.

Abstract: A system and method for improving storage system performance by reducing or avoiding load spike amplification when performing garbage collection is disclosed. A storage controller in a storage system tracks system load including write load and read load, as well as available free segments. The storage controller uses these tracked values as inputs and, with these inputs, generates a garbage collection rate. Where read load is included, a scaled portion of the read load is taken into consideration so that, as the number of free segments nears the minimum amount desired and to prevent garbage collecting too slowly, the read load is gradually excluded from the garbage collection rate determination. The garbage collection rate is therefore responsive to system load so that, in times of high system load, the rate reduces as much as is safe so that the write load takes priority with computing resources of the storage controller.

Abstract: A storage system comprises a plurality of storage devices, and is configured to establish a redundant array of independent disks (RAID) arrangement comprising a plurality of stripes, with each of the plurality of stripes comprising a plurality of blocks, the blocks being distributed across multiple ones of the storage devices. In conjunction with establishment of the RAID arrangement, the storage system is further configured, for each of the plurality of stripes, to designate multiple ones of the storage devices as respective spare devices for that stripe, and for each of the storage devices, to determine numbers of the stripes for which that storage device is designated as a spare device for respective ones of the other storage devices in each of multiple spare levels and for each of multiple failure combinations. A particular number of spare blocks is reserved for each of the storage devices using the determined numbers.

Abstract: A device access apparatus for a client-server system is described, wherein the device access apparatus is used to access components of a field bus network. The device access apparatus includes a general application that is installable on a server and configured to interchange data with the components of the field bus network. The device access apparatus also includes a device driver that is installable on a client and a communication proxy that is installable on the server that are configured to set up a data connection between the server and the client. The data connection is used to transmit data between the device driver and one of the components of the field bus network that is associated with the device driver. The communication proxy is configured to monitor data traffic on the data connection between the client and the server and detect errors in the data transmission.

Abstract: A storage system comprises a plurality of enclosures and a storage controller. Each enclosure comprises at least one processing device and a plurality of drives configured in accordance with a redundant array of independent disks (RAID) arrangement. The storage controller obtains an input-output request to read a target data page and issues a command to the at least one processing device of a given enclosure. Responsive to receiving the command, the at least one processing device of the given enclosure obtains data pages associated with a given stripe from the plurality of drives of the given enclosure. The at least one processing device rebuilds the given stripe based at least in part on the obtained data pages, obtains the target data page from the rebuilt given stripe and provides the obtained target data page to the storage controller.

Abstract: Method and system are provided for handling an underperforming drive in a redundant array of independent disks (RAID) operating a distributed sparing mechanism. The method includes marking an underperforming drive in the array as resting and allocating distributed spare space of the array for data of operations to the resting drive. A data structure is designated to track operations diverted to the distributed spare space from the resting drive. If the resting drive is recovered, the method rebuilds data to the recovered drive from the distributed spare space by reference to the data structure.

Abstract: Methods and apparatus for use in a dispersed storage network (DSN) to facilitate coordination between dispersed storage computing devices and dispersed storage integrity processing unit rebuild modules. In one example, data may be rebuilt in a DSN by determining a rebuild task to be executed based on an attempt to access data in the DSN. Status information regarding the rebuild task is then generated and forwarded to the dispersed storage computing device and/or one or more dispersed storage units for subsequent attempts to access data in the DSN.

Abstract: Embodiments of the present disclosure provide a method and a device for managing storage system. In an embodiment, a plurality of RAID stripes to be reconstructed in the storage system are determined. A first RAID stripe is selected from a plurality of RAID stripes based on a plurality of I/O load states at a disk extent level for the plurality of RAID stripes at a first storage processor in the storage system, the first RAID having a high I/O load at the disk extent level. Then, a first disk extent for reconstructing the first RAID stripe is determined and the first storage processor is configured to reconstruct data for the first RAID stripe at the first disk extent. A corresponding device to implement the method is further disclosed.

Abstract: Techniques manage a storage system. The storage system includes at least one part of multiple storage devices, here respective storage devices among the multiple storage devices include a first portion and a second portion, the first portion is for storing data and the second portion is reserved for rebuilding the storage system. The techniques involve: determining a storage device in the at least one part of storage devices fails; recovering data in a first portion of the failed storage device on the basis of data in a first portion of a normal storage device other than the failed storage device in the at least part of storage devices; selecting a group of storage devices from normal storage devices among the multiple storage devices; and writing recovered data to a second portion in the group of selected storage devices. Thereby, the speed of rebuilding the storage system may be increased, and further the overall performance of the storage system may be enhanced.

Abstract: Example storage systems, storage controllers, and methods provide data redundancy reconfiguration using logical subunits. Storage devices are configured in a storage group with a first data redundancy configuration. A second data redundancy configuration is selected and the space available in the storage group is determined. For each logical data unit, logical data subunits are selected, written to the space available in the second data redundancy configuration, and deleted from the logical data unit. Storage operations using the storage group may be maintained during the migration process.

Abstract: A Distributed Availability Group (DAG) spans two AGs, each spanning one or more replica nodes and functioning as primary or secondary AG. A primary AG is replicated to the secondary AG synchronously or asynchronously. A failover in the DAG results in the AGs swapping their roles. Multiple DAGs can be linked together as a chain, which provides many useful features including disaster recovery across geographical regions, massive read scale (numerous readable secondary nodes), online migration of databases (across different operating systems and computing environments). The systems using DAGs can replicate databases across multiple independent high availability (HA) failover clusters using complex replication topologies and allow for manual failover and failback. The systems allow chaining of multiple AGs to provision a treelike structure of replicas and numerous secondary replicas without impacting performance.

Abstract: User data to be stored at a data block location of a plurality of data block locations at a storage system may be received. A parity data based on the received user data may be generated. An indication of an occurrence of an event associated with the storage system may be received. In response to receiving the indication of the occurrence of the event, the parity data may be stored by a processing device at a particular data block location of the plurality of data block locations where the particular data block location is situated prior to another data block location, of the plurality of data block locations, that is to store another parity data based on a subsequent user data.

Abstract: Example redundant array of independent disks (RAID) storage systems and methods provide rebuild of logical data groups in priority order. Storage devices are configured as a storage array for storing logical data groups distributed among the storage devices. The logical data groups are written in a configuration of RAID stripes in the storage devices. A logical group index includes a logical group map for each logical data group and identifies corresponding logical blocks. When a storage device fails, the rebuild queue is ordered based on the priority of the logical data groups and rebuild to the replacement storage device is completed in the priority order.

Abstract: A variety of applications can include apparatus and/or methods that provide parity protection to data spread over multiple memory devices of a memory system. Parity is stored in a buffer, where the parity is generated from portions of data written to a page having a different portion of the page in a portion of each plane of one or more planes of the multiple memory devices. Parity is stored in the buffer for each page. In response to a determination that a transfer criterion is satisfied, the parity data in the buffer is transferred from the buffer to a temporary block. After programming data into the block to close the block, a verification of the block with respect to data errors is conducted. In response to passing the verification, the temporary block can be released for use in a next data write operation. Additional apparatus, systems, and methods are disclosed.

Abstract: A method of monitoring a plurality of storage devices using a storage management system includes receiving and analyzing input/output data related to the storage devices and generating a model in response to the monitoring, including the detected input/output data related to at least a first and a second storage device, and where the input/output data includes at least one measurable storage device aspect. The method also includes determining, in response to the generating, that the first storage device is a control storage device, and that the second storage device is to be compared to the first storage device and comparing the input/output data of the second storage device to the first storage device according to the at least one measurable storage device aspect. The method also includes determining that the second storage device is operating sub-optimally and transmitting a notification that the second storage device is operating sub-optimally.

Abstract: In one implementation, a method includes detecting, by a storage system controller associated with a plurality of storage devices, a first anomaly corresponding to a first data shard of a redundant array of independent disks (RAID) group and determining, by the storage system controller, that the first anomaly corresponding to the first data shard is not to be corrected within the RAID group. The method further includes removing the first data shard from the RAID group and recalculating, by the storage system controller, one or more error recovery codes corresponding to the RAID group from a plurality of remaining data shards of the RAID group, without the first data shard.

Abstract: A system and method improve the performance of non-volatile memory storage by rebuilding, on the fly, “lost data” in response to a read request, which identifies data to be read or recovered, by identifying a parity data storage device in a set of data storage devices that contains parity corresponding to the identified data; sending a reconstruction request to a respective data storage device, which may be the parity data storage device or other data storage device in the system, to reconstruct the identified data, and receiving the identified data from the respective data storage device. The reconstruction request commands the respective data storage device to retrieve, via peer-to-peer read requests, from other data storage devices, data from one or more data blocks, and to reconstruct the identified data based on the retrieved data and parity data locally stored at the parity data storage device.

Abstract: A method writing data received from a host device includes determining whether command data of a write command includes metadata, flushing the command data out of a volatile write cache according to a first caching policy responsive to a determination that the command data does includes metadata, and flushing the command data out of the volatile write cache according to a second different caching policy responsive to a determination that the command data does not include metadata.

Abstract: A method is proposed for processing a data word, in which the data word comprises a first partial data word and a second partial data word, in which first checkbits are defined for the first partial data word, wherein the first partial data word and the first checkbits form a first codeword, in which second checkbits are defined for the second partial data word, wherein the second partial data word and the second checkbits form a second codeword, in which third checkbits are defined for the data word, wherein at least (i) the data word, (ii) a linking of the first checkbits with the second checkbits, and (iii) the third checkbits are parts of a third codeword.

Abstract: a method and an apparatus for maintaining reliability of a mapped redundant array of independent disks. The method comprises: determining a first data loss probability, the first data loss probability indicating reliability of a traditional redundant array of independent disks; determining a second data loss probability, the second data loss probability indicating reliability of the mapped redundant array of independent disks; and determining, based on the first and second data loss probabilities, a condition for maintaining the reliability of the mapped redundant array of independent disks. Compared with the prior art, embodiments of the present disclosure can effectively predict the reliability of a mapped RAID through comparison with a traditional RAID, so as to be capable of determining a reliability relationship between the traditional RAID and the mapped RAID. In this way, the reliability of the traditional RAID will not be degraded when being expanded into the mapped RAID.

Abstract: Provided is a data management system including a master group including a data manager configured to manage data, a process manager configured to manage a process of analyzing the data, and a meta data storage unit configured to store meta data information for managing the data; and at least one work group including a work manager configured to manage resources, the data, and a data process on the basis of a scope of groups, and at least one node manager configured to manage the resources, the data, and the data process on the basis of a scope of nodes. The master group and the at least one work group are dispersed from each other.