Abstract: The disk drives of an array are organized into clusters of multiples of G+1 drives with G same-size indexed subdivisions, where G is the number of members in a protection group. G+1 groupings are created in each cluster, including G groupings distributed over G drives in single subdivision indices and one grouping distributed diagonally over multiple subdivision indices. A single grouping in at least one cluster is configured as spare capacity. Protection groups are located in the other groupings. Drive IO loading is rebalanced by swapping the location of a selected protection group with the location of the spare grouping. The protection group to be relocated may be selected by using LOF scores to identify a cluster with IO loading outlier drives that are overloaded and then calculating IO loading that would result from swapping locations of each protection group in that cluster with the spare grouping.

Abstract: A software-defined, server-based storage system is configured to support single node granular scaling and adaptive RAID width capabilities. The storage system includes multiple homogeneous storage nodes, each including a server and local storage. Aggregate storage is organized into same-size cells. RAID group members are distributed in cells across storage nodes in a recursive fractal pattern. The storage system is scaled by metamorphosing between recursive fractal distribution of the RAID groups and linear distribution of the RAID groups and splitting matrices of cells. When a sufficient number of new storage nodes have been added, new larger width RAID groups will be formed.

Abstract: A drive subset matrix is created with at least N+1 drives each having N*N same-size subdivisions. Conceptually, N submatrices are created along with spares equivalent to at least one drive of storage capacity. The spares are located such that every drive has an equal number of spares +/?1. One protection group is located in a lowest indexed subdivision of each of the submatrices. Members of other protection groups are located by selecting members in round robin order and placing each selected member in a free subdivision having a lowest drive index and lowest subdivision index. The drive subset can be grown, split, and reorganized to restore balanced and efficient distribution of spares.

Abstract: An initial drive cluster of G drives with G subdivisions is represented by a G*G drive matrix, where G equals the number of data and parity members in the RAID level implemented on the drive cluster. A corresponding G×G overlay matrix is created in which a value at row R, column C equals a remainder of (R+C?2) divided by G, such that there are G distinct values in a range of 0 to G?1. Responsive to addition of N new drives to the drive cluster, the N new drives are added to the drive matrix and the overlay matrix is used to select and relocate RAID members within the drive matrix so that new RAID groups can be created.

Abstract: A drive subset matrix is created with at least N+1 drives each having N*N same-size subdivisions. Conceptually, N submatrices are created along with spares equivalent to at least one drive of storage capacity. The spares are located such that every drive has an equal number of spares +/?1. One protection group is located in a lowest indexed subdivision of each of the submatrices. Members of other protection groups are located by selecting members in round robin order and placing each selected member in a free subdivision having a lowest drive index and lowest subdivision index. The drive subset can be grown, split, and reorganized to restore balanced and efficient distribution of spares.

Abstract: In a storage system that implements RAID (D+P) protection groups a drive subset initially has (D+P) drives plus a spare drive with (D+P) splits. Spare splits are distributed with drive index and split index adjacency such that no single drive or split index contains multiple spare splits. When the drive subset is incremented by one drive a group of selected splits are relocated to the new drive based on drive index and split index adjacency such that no single drive or split index contains multiple members of a new protection group. If one of the drives is failing or fails, then an adjusted spare split index value is calculated for each protection group member on that drive so that the protection group members are rebuilt or relocated without placing more than one member of any protection group on a single drive. Adjusted spare split index values may be calculated in steps using the data split indices in ascending order and the largest drive indices in descending order.

Abstract: A storage system has a plurality of storage nodes having equal non-volatile storage capacity that is subdivided into equal size cells. Host application data that is stored in the cells is protected using RAID or EC protection groups each having members stored in ones of the cells and distributed across the storage nodes such that no more than one member of any single protection group is stored by any one of the storage nodes. Spare cells are maintained for rebuilding protection group members of a failed one of the storage nodes on remaining non-failed storage nodes so full data access is possible before replacement or repair of the failed storage node.

Abstract: A storage system memory or memory domain with N memory controllers is organized into N-1 same-size partitions per memory controller or N partitions per memory controller with one partition reserved as spare capacity. The unreserved partitions are assigned to mirror pairs of members such that a first triangular submatrix of a representative matrix of indexed memory controllers and indexed partitions is a transpose of a second triangular submatrix of the representative matrix. The resulting distribution of members is balanced such that additional loading on remaining memory controllers when one of the memory controllers becomes inaccessible is evenly distributed.

Abstract: Mirrored pairs in a RAID-1 are distributed in a balanced and deterministic way that increases data access parallelism. For a group of k+1 disks that can be represented as a matrix of disk rows indexed 0 through k, where each disk is organized into k same-size subdivisions, in columns indexed 1 through k, corresponding mirrors of data members on the first disk (row index 0) are distributed across all other disks along a matrix diagonal such that the row index is the same as the column index for each mirror. Additional mirror pairs are created and symmetrically distributed in two submatrix triangles that are defined and separated by the diagonal. The two triangles are populated with symmetrically distributed mirrors that are flipped around the matrix diagonal such that for any mirror data in one triangle, its corresponding mirror data can be found in the other triangle by swapping the row and column indices.

Abstract: One or more aspects of the present disclosure relate to recovering at least one failed disk. In embodiments, determining a storage reserve capacity allocated for recovering at least one storage device of a storage array is determined. Zero or more storage portions from each storage device of at least one storage cluster for disk recovery are adaptively assigned based on the storage reserve capacity. The failing and/or failed disk using the assigned storage portions is recovered in response to detecting a failing and/or failed disk.

Abstract: The lifespans of the solid stated drives (SSDs) of a storage array are modelled using linear regression with monitored wear level and power-on time. The models predict when individual SSDs will reach a wear level corresponding to readiness for replacement. A drive replacement process makes efficient use of available empty drive slots to replace SSDs in batches. SSDs that are ready for replacement are ranked in terms of priority for replacement. If the number of SSDs that are ready for replacement exceeds the number of available empty drive slots, then ranking us used to assign individual SSDs to different batches for replacement.

Abstract: Physical storage devices (PSDs) of a protection group cluster (PGC) may be represented by a protection group matrix (PGM) having a plurality of rows and a plurality of columns, where each row corresponds to a PSD of the PGC, and each column corresponds to a partition of each PSD. The value specified in each cell at an intersection of a row and column specifies the protection group of the PGC to which the partition of the PSD represented by the column and row, respectively, is (or will be) assigned. In response to one or more of PSDs being added to a PGC, the PGM may be reconfigured, including adding new rows, and transposing portions of columns to the new rows, or transposing portions of rows to portions of columns of the new rows. Protection members of the PGC may be re-assigned based on the reconfiguration.

Abstract: The over-provisioning (OP) of a physical storage device (PSD) may be increased, and the useful life of the PSD increased, by converting uncompressed data stored on the PSD to compressed data. It may be determined that increasing the useful life of the PSD, and the data reduction resulting from the compression, outweigh the benefit of faster I/O response times if the data remains uncompressed. A first portion of the PSD may be initially reserved for compression. A second portion of the PSD may store compressed data. It may be determined whether it is desirable to increase the OP of the PSD to thereby reduce the effective write rate on the PSD. If compression is determined to be desirable, the dynamic portion may be compressed, thereby reducing the amount of storage space consumed by the data, and freeing up storage space that can be used by the PSD for OP.

Abstract: The lifespans of the solid stated drives (SSDs) of a storage array are modeled using linear regression with monitored wear level and power-on time. The models predict when individual SSDs will reach a wear level corresponding to readiness for replacement. A drive replacement process makes efficient use of available empty drive slots to replace SSDs in batches. SSDs that are ready for replacement are ranked in terms of priority for replacement. If the number of SSDs that are ready for replacement exceeds the number of available empty drive slots, then ranking us used to assign individual SSDs to different batches for replacement.

Abstract: 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.

Abstract: 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.

Abstract: A storage system has a plurality of storage nodes having equal non-volatile storage capacity that is subdivided into equal size cells. Host application data that is stored in the cells is protected using RAID or EC protection groups each having members stored in ones of the cells and distributed across the storage nodes such that no more than one member of any single protection group is stored by any one of the storage nodes. Spare cells are maintained for rebuilding protection group members of a failed one of the storage nodes on remaining non-failed storage nodes so full data access is possible before replacement or repair of the failed storage node.

Abstract: Physical storage devices (PSDs) of a protection group cluster (PGC) may be represented by a protection group matrix (PGM) having a plurality of rows and a plurality of columns, where each row corresponds to a PSD of the PGC, and each column corresponds to a partition of each PSD. The value specified in each cell at an intersection of a row and column specifies the protection group of the PGC to which the partition of the PSD represented by the column and row, respectively, is (or will be) assigned. In response to one or more of PSDs being added to a PGC, the PGM may be reconfigured, including adding new rows, and transposing portions of columns to the new rows, or transposing portions of rows to portions of columns of the new rows. Protection members of the PGC may be re-assigned based on the reconfiguration.

Abstract: A storage system has a plurality of heterogenous storage nodes characterized by non-uniform total non-volatile storage capacity. Storage capacity of all nodes is configured as same-size cells and represented as a set of matrices. The matrices have dimensions corresponding to consecutive cell indices and consecutive storage node indices. Initially, storage nodes having the same storage capacity are consecutively indexed so that the representative matrices are not ragged due to gaps, referred to herein as non-contiguous storage space, where cells do not exist because of differences in numbers of cells in adjacently indexed storage nodes. Addition of more heterogeneous storage nodes can create such gaps when the cells of those storage nodes are added to the matrices.

Abstract: Protection group members from a cluster of W baseline size disks with RAID (D+P) protection groups associated with W partition indices, where W=D+P, are selected and relocated to a new baseline size disk using a W-by-W relocation sequence matrix. The same relocation sequence matrix is used to select and relocate protection group members from M clusters of baseline size disks to a new disk that has M times the storage capacity of each baseline size disk. A new cluster of multiple size disks is formed when W multiple size disks have been added, after which the W-by-W relocation sequence matrix is used to select and relocate protection group members from the new cluster to additional multiple size disks.