Intel® Volume Management Device (VMD)
The Intel® Xeon Scalable series processors based on Skylake-SP feature a new Volume Management Device (VMD) built-in. This feature will seem similar to VROC (Virtual RAID On CPU), which debuted with the Core X series and X299 chipset, but VMD is what actually enables VROC.
Each CPU has 3 VMD domains that manages 16 PCIe lanes (total 48 lanes per CPU). The Intel® VMD can be turned on and of in the BIOS per 4 lanes (x4 PCIe SSD)
The total number of PCIe lanes in a dual socket machine equals 96 (2×48) and can be devided in max. 24 NVMe drives that are directly attached to the CPU in the system.
Intel® Virtual RAID on CPU (VROC)
Intel® VROC is and Enterprise RAID solution specifically designed for NVMe SSD’s
RAID can be built within a Single VMD domain but also across domains, and even across CPU’s
A RAID array can be bootable when they remain within a single VMD domain. RAID arays that span across multiple VMD domains are not bootable.
Because the Intel® VROC creates RAID arrays without using a traditional RAID HBA the performance is much higher.
Intel® VROC is a hybrid RAID solution. It has attributes like hardware RAID because of the key silicon feature, Intel® Volume Management Device (Intel® VMD). Intel® VDM is offered with the new Intel® Xeon® Scalable Processors. Intel® VROC utilizes Intel® VMD to aggregate NVMe SSDs allowing bootable RAID. Intel® VROC also has attributes like software RAID. For instance, it uses some of the CPU cores to calculate the RAID logic. Because of this combination of software and silicon, Intel® VROC is called a hybrid RAID solution.
Intel® VROC replaces the NVMe RAID. Intel VROC uses Intel® Volume Management Device (Intel® VMD) to provide these new features that Intel® RSTe legacy NVMe RAID does not have:
- Bootable RAID
- Surprise hot-plug
- LED management
- RAID5 Double Fault Protection
- Support for third-party SSDs