Author:
Subject: Storage
Manufacturer: ASUS

Is it a usable feature?

EDIT: We've received some clarification from Intel on this feature:

"The feature is actually apart of RST. While this is a CPU-attached storage feature, it is not VROC. VROC is a CPU-attached PCIe Storage component of the enterprise version of the product, Intel RSTe. VROC requires the new HW feature Intel Volume Management Device (Intel VMD) which is not available on the Z370 Chipset.

The Intel Rapid Storage Technology for CPU-attached Intel PCIe Storage feature is supported with select Intel chipsets and requires system manufacturer integration. Please contact the system manufacturer for a list of their supported platforms."

While this doesn't change how the feature works, or our testing, we wanted to clarify this point and have removed all references to VROC on Z370 in this review.

While updating our CPU testbeds for some upcoming testing, we came across an odd listing on the UEFI updates page for our ASUS ROG STRIX Z370-E motherboard.

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From the notes, it appeared that the release from late April of this year enables VROC for the Z370 platform. Taking a look at the rest of ASUS' Z370 lineup, it appears that all of its models received a similar UEFI update mentioning VROC. EDIT: As it turns out, while these patch notes call this feature "VROC", it is officially known as "Intel Rapid Storage Technology for CPU-attached Intel PCIe Storage " and slightly different than VROC on other Intel platforms.

While we are familiar with VROC as a CPU-attached RAID technology for NVMe devices on the Intel X299 and Xeon Scalable platforms, it has never been mentioned as an available option for the enthusiast grade Z-series chipsets. Could this be a preview of a feature that Intel has planned to come for the upcoming Z390 chipset?

Potential advantages of a CPU-attached RAID mode on the Z370 platform mostly revolve around throughput. While the chipset raid mode on the Z370 chipset will support three drives, the total throughput is limited to just under 4GB/s by the DMI 3.0 link between the processor and chipset.

Like we've seen AMD do on their X470 platform, CPU-attached RAID should scale as long as you have CPU-connected PCI-Express lanes available, and not being used by another device like a GPU or network card.

First, some limitations.

Primarily, it's difficult to connect multiple NVMe devices to the CPU rather than the chipset on most Z370 motherboards. Since the platform natively supports NVMe RAID through the Z370 chipset, all of the M.2 slots on our Strix Z370-E are wired to go through the chipset connection rather than directly to the CPU's PCIe lanes.

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To combat this, we turned to the ASUS Hyper M.2 X16 card, which utilizes PCIe bifurcation to enable usage of 4 M.2 devices via one PCI-E X16 slot. Luckily, ASUS has built support for bifurcation, and this Hyper M.2 card into the UEFI for the Strix Z370-E.

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Aiming to simplify the setup, we are using the integrated UHD 620 graphics of the i7-8700K, and running the Hyper M.2 card in the primary PCIe slot, usually occupied by a discrete GPU.

Continue reading our look at CPU-attached NVMe RAID on Z370 motherboards from ASUS!