Product : Pivot3, Acuity [HCI]/10.6.1, Datacenter
Feature : Persistent Write Buffer, Reads/Writes, Data Availability
Content Owner:  Herman Rutten
NVMe PCIe (mirrored)
NVMe PCIe serves as a very performant storage medium for a read/write mirrored journal that is split between two accelerator nodes.

When an application sends a write request, it is mirrored between the NVMe PCIe flash cards on two Acuity X3/X5 Accelerator nodes for high availability and redundancy. Once both copies are stored, the receiving node acknowledges the write completion to the host. Once the write is acknowledged, the system will copy the data from NVMe PCIe flash to disk (HDD or SSD). Reads, writes, and modifies of the original copy occur in NVMe PCIe flash. At this point, the copy on disk is only used in the event that a rebuild on the NMVe PCIe flash tier is required. Lastly, if the data that is stored in NVMe PCIe flash is not being accessed frequently, the Acuity X5 node will evict it to make room for more active data based on the QoS priorities and targets. The decision to evict data is made in real-time based on access patterns, current performance levels and data-reduction ratios.

NVMe flash is able to deliver 2x the performance of 12Gbps SAS and up to 6x the performance of 6Gbps SATA.

Pivot3 Acuitys platform architecture requires two Flash Accelerator nodes to be part of any virtual Performance Group (vPG aka "cluster"), regardless if SSD or HHD is placed underneath.

NVMe = Non-volatile memory express
PCIe = Peripheral Component Interconnect Express