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: 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 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.

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.

Abstract: In a storage system that implements RAID (D+P) protection groups a drive subset initially has (D+P) drives with (D+P) partitions. The drive subset is made to be symmetrical such that protection group members are symmetrically distributed in a matrix of drive rows and partition columns that represents the drive subset. A single new drive is added by partitioning the new drive with (D+P) partitions, moving existing protection group members from a selected partition of the (D+P) drives to partitions of the single new drive by rotating the selected partition by 90 degrees, and adding protection group members of a new protection group to the vacated selected partition of the (D+P) drives. The process is repeated until (D+P) new drives have been added in single drive increments. The resulting drive subset is then split by forming a non-symmetric drive subset from the (D+P) drives and forming a symmetric drive subset from the (D+P) new drives.

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: A storage array includes a scalable drive cluster and non-scaling drive clusters on which RAID (D+P) protection groups are implemented using partition as protection group members. The scalable drive cluster is scaled by adding one or more new drives and moving protection group members onto the new drives. Reserve capacity is calculated based on scaling of the scalable drive cluster by converting unused partitions to reserve capacity when the cluster is scaled. When W=(D+P) new drives are added to the storage array the reserve capacity is replenished, if any was used, by moving protection groups from the scalable drive cluster to a non-scaling drive cluster created with the W new drives. Maintaining the reserve capacity on the scaling drive cluster improves function of the storage array because unutilized reserve capacity can be relocated during scaling without moving data.

Abstract: A flexible RAID system can expand by iteratively adding disks to a disk cluster. The disks may be added individually or in groups. Spare capacity is distributed over multiple disks within a cluster. Clusters are created, grown, and divided with predictable RAID member distribution patterns. Cluster validation is performed based on the patterns.

Abstract: A subset of drives with protection groups that have D data members and P parity members is created with (W+1) drives each having W partitions where W=(D+P). A single partition protection group is created in the lowest numbered partition of the W lowest numbered drives. Spares are created at drive X partition Y that satisfy X+Y=W+2. Members of additional protection groups with W members are symmetrically distributed on remaining partitions such that the protection group member at drive X partition index Y belongs to protection group N: if (X+Y)<(W+2), then N=(X+Y?2); and if (X+Y)>(W+2), then N=(X+Y?W?2). The spares are used to rebuild partitions in the event of drive failure. When a new drive is added the first W protection group members in the lowest numbered unrotated partition are rotated onto the new drive. The single partition protection group is excluded from rotation. Partitions vacated by rotated protection group members and a rotated spare are used to create a new protection group.

Abstract: A storage array includes a scalable drive cluster and non-scaling drive clusters on which RAID (D+P) protection groups are implemented using partition as protection group members. The scalable drive cluster is scaled by adding one or more new drives and moving protection group members onto the new drives. Reserve capacity is calculated based on scaling of the scalable drive cluster by converting unused partitions to reserve capacity when the cluster is scaled. When W=(D+P) new drives are added to the storage array the reserve capacity is replenished, if any was used, by moving protection groups from the scalable drive cluster to a non-scaling drive cluster created with the W new drives. Maintaining the reserve capacity on the scaling drive cluster improves function of the storage array because unutilized reserve capacity can be relocated during scaling without moving data.