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PowerStore can be configured with NVMe SSDs or SCM drives for user data. SSD-based systems can be expanded with additional drives to increase the amount of available storage capacity. PowerStore 1000, 3000, 5000, 7000, and 9000 series models can be expanded with SAS SSD-based expansion shelves.
Starting from PowerStoreOS 3.0, all PowerStore models can be expanded with NVMe SSD-based expansion shelves if they satisfy the hardware prerequisites in the Dell PowerStore: Introduction to the Platform White Paper. Dell Technologies recommends that all drives in a PowerStore system be the same size, which can maximize the usable capacity from each drive.
PowerStore Dynamic Resiliency Engine (DRE) is used to manage the drives in the system. All drives are automatically used to provide storage capacity. DRE groups the drives into resiliency sets to protect against drive failure. User configuration of the drives is not necessary, and dedicated hot spare drives are not required. Spare space for rebuilds is automatically distributed across all drives within each resiliency set. This configuration provides better resource utilization and enables faster rebuilds in the event of a drive failure.
Aside from PowerStore 500, PowerStore systems use NVMe NVRAM drives to provide persistent storage for cached write data. PowerStore 1000 to 3200 arrays have two NVRAM drives per system, while PowerStore 5000 to 9200 arrays have four NVRAM drives per system. The extra drives mean that these systems can provide higher MBPS for large-block write workloads.
The following figure shows how the NVRAM drives are configured in the base enclosure:
Aside from the 500T model, NVMe SSD-based systems can also be expanded with an expansion enclosure using up to 24 SAS SSD drives to increase the amount of available storage capacity:
NVMe SCM drives are dual-ported, extreme-high-performance, nonvolatile drives that are designed with Intel Optane technology. The PowerStore operating system accesses these drives with NVMe. NVMe SCM drives have lower latency and improved performance compared to other SSD drives.
NVMe SCM drives serve as a storage tier for PowerStore, are used for user data or metadata, and come at a capacity point of 750 GB. PowerStore can use SCM drives either by having only SCM drives installed in the system or by mixing SCM and SSD drives, as with PowerStoreOS 2.0 and later. Systems with all-SCM drives are recommended for small-block workloads that require the absolute lowest latencies. A system with all-SCM drives places both data and metadata on the SCM drives. Systems with mixed SSD and SCM drives use the SCM drives for metadata acceleration; and the SCM drives store metadata for faster lookups. This configuration can reduce latency on read operations in systems with large physical capacities. When mixing SCM and SSDs, Dell Technologies recommends that at least five percent of the system’s physical capacity be SCM.
For SAP HANA, we recommend using NVMe SSDs with a disk capacity size that allows the system capacity to fit within the base enclosure. Use a minimum of ten drives for single-drive failure tolerance, or nineteen drives for double-drive failure tolerance. Dell Technologies tested SAP HANA performance and scalability with single parity (single tolerance R5) and dual parity (double tolerance R6) and found that the performance levels were the same for both. The SAP HANA scalability in Table 3 (FC SAN) and Table 4 (NAS/NFS) is therefore valid for both single-drive and double-drive failure tolerance levels.