Reconfiguring a storage system based on resource availability, including: limiting a number of storage devices in a storage system that may be simultaneously servicing write operations; determining that an amount of required write bandwidth has changed; and subsequent to determining that the amount of required write bandwidth has changed, adjusting, by a computer processor, the number of storage devices in the storage system that may be simultaneously servicing write operations.

Embodiments of the present disclosure relate to methods, devices and computer program products for writing data in a disk array in a storage system. The storage system comprises a disk array. The method comprises: in response to receiving a write request to write new data to a data block in at least one disk array group in a degraded mode within a disk array, reading old data stored in the data block and old parity information stored in a parity block associated with the data block. The method further comprises: determining new parity information associated with the new data based on the old data, the old parity information and the new data. The method further comprises: writing the new data and the new parity information into at least one cache page provided by a cache component in the storage system, the at least one cache page being allocated in a persistent memory in the cache component. In addition, this method further comprises: flushing the new data and the new parity information into the data block and the parity block in the at least one disk array group, respectively.

Techniques for managing a redundant array of independent disks (RAID) involve detecting an abnormality of a storage device in a RAID. The techniques further involve resetting the storage device in response to detecting the abnormality. The techniques further involve storing an address of a write operation for the RAID within a preset time period, so as to rebuild the RAID in the case that the storage device is recovered within the preset time period. Accordingly, temporary errors of the RAID can be efficiently handled, the number of downtime of the RAID caused by the storage device or the back end can be reduced, and computing resources and time required to rebuild the RAID can be significantly reduced.

Embodiments herein provide a method for controlling operations of a Redundant Array of Independent Disks (RAID) data storage system comprising a host device and a plurality of solid-state drives (SSDs). The method includes performing, by the at least one SSD, recovery of lost data by performing the auto-rebuild operation. The method also includes performing by the at least one SSD, the auto-error correction operation based on the IO error. The method also includes creating a snapshot of an address mapping table by all SSDs of the plurality of SSDs in the RAID data storage system. The auto-rebuild operation, the auto-error correction operation and the creation the snapshot of the address mapping table are all performed without the intervention from the host device.

Managed drives of a storage node with different size drives in a fixed arithmetic relationship are organized into clusters of same size drives. Every drive is configured to have M*G same-size partitions, where M is a positive integer variable defined by the arithmetic relationship and G is the RAID group size. The storage capacity of all drives can be viewed as matrices of G+1 rows and M*G columns, and each matrix is composed of submatrices of G+1 rows and G columns. Diagonal spare partitions are allocated and distributed in the same pattern over groups of G columns of all matrices, for increasing partition index values. Members of RAID groups are vertically distributed such that the members of a given RAID group reside in a single partition index of a single cluster. When a drive fails, protection group members of the failed drive are rebuilt in order on spare partitions characterized by lowest partition indices for increasing drive numbers across multiple clusters. Consequently, drive access for rebuild is parallelized and latency is reduced.

A system and method for providing erasure code protection across multiple storage devices. A data switch in a storage system connects a plurality of storage devices to a remote host. Each storage device is also connected to a controller, e.g., a baseboard management controller. During normal operation, read and write commands from the remote host are sent to respective storage devices through the data switch. When a write command is executed, the storage device executing the command sends a copy of the data to the controller, which generates and stores erasure codes, e.g., on a storage device that is dedicated to the storage of erasure codes, and invisible to the remote host. When a device fails or is removed, the controller reconfigures the data switch to redirect all traffic addressed to the failed or absent storage device to the controller, and the controller responds to host commands in its stead.

Provided are mechanisms for promptly or gradually migrating data from a read-only disk in a storage system to a replacement disk, where, during gradual migration, data is migrated when it is requested of the read-only disk.

A method comprising: receiving a request to read data stored in an array of drives; determining that the data is stored on one or more degraded drives in the array; reconstructing the data from one or more drives in the array other than the degraded drives; providing the reconstructed data in response to the request; and after providing the reconstructed data, writing the reconstructed data to one or more drives in the array other than the degraded drives.

Techniques perform data access to a disk array. The disk array includes a parity disk and a plurality of data disks. Via such techniques, data is written to the parity disk in the disk array in response to a write request to a failed data disk in the disk array when the disk array is in a degraded state; and corresponding degraded storage position information is set in disk resource mapping information so as to indicate that the data are stored in the parity disk. Accordingly, enormous computing resources can be saved, and I/O operations required by reads in the degraded state can be reduced.

A method of operating a storage device may include determining a fault condition of the storage device, selecting a fault resilient mode based on the fault condition of the storage device, and operating the storage device in the selected fault resilient mode. The selected fault resilient mode may include one of a power cycle mode, a reformat mode, a reduced capacity read-only mode, a reduced capacity mode, a reduced performance mode, a read-only mode, a partial read-only mode, a temporary read-only mode, a temporary partial read-only mode, or a vulnerable mode. The storage device may be configured to perform a namespace capacity management command received from the host. The namespace capacity management command may include a resize subcommand and/or a zero-size namespace subcommand. The storage device may report the selected fault resilient mode to a host.