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PowerStore can be configured with NVMe solid-state devices (SSDs) or NVMe storage class memory (SCM) drives for user data. The 3200Q model only supports QLC NVMe SSDs, while all other PowerStore model appliances support TLC NVMe SSDs. Mixing QLC and TLC drives within a single appliance is not supported. SSD-based systems can be expanded with additional drives to increase the amount of available storage capacity. PowerStore 1000, 3000, 5000, 7000, and 9000 models can be expanded with SAS SSD-based expansion shelves. Starting in PowerStoreOS 3.0, all PowerStore models, including the 3200Q, can be expanded with NVMe SSD-based expansion shelves if they meet the necessary hardware prerequisites defined in the white paper Dell PowerStore: Introduction to the Platform. It is recommended that all drives within a PowerStore system be the same size, which can maximize the usable capacity of 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 in PowerStore. Spare space for rebuilds is automatically distributed across all drives within each resiliency set. This configuration provides better resource utilization and enables faster rebuilds if there is a drive failure.
At initial installation of the PowerStore system, DRE can be configured with either single- or double-drive failure tolerance. To provide the greatest usable capacity from the same number of drives, it is recommended to initially install PowerStore with a minimum of ten drives for single-drive failure tolerance, or nineteen drives for double-drive failure tolerance. PowerStore 3200Q models require a minimum of eleven drives, and double-drive failure tolerance is enforced on the appliance.
PowerStore can use SCM drives either by having only SCM drives installed in the system, or, with PowerStoreOS 2.0 or higher, by mixing SCM and TLC model SSD drives.
Systems with all SCM drives are recommended for small-block workloads that require the absolute lowest latencies. A system with all SCM drives will place both data and metadata on the SCM drives.
Systems with mixed SSD and SCM drives will use the SCM drives for metadata acceleration; the SCM drives will store metadata for faster lookups. This can reduce latency on read operations in systems with large physical capacities. When mixing SCM and SSDs, it is recommended that at least 5 percent of the system’s physical capacity should be SCM.