Template:Tri-mode

Tri-Mode

Tri-mode

According to OCP-Trimode-Presentation, SAS and NVMe forecasted to increase over the coming years and SATA to decrease.

U.3 is a ‘Tri-mode’ standard, building on the U.2 spec and using the same SFF-8639 connector. It combines SAS, SATA, and NVMe support into a single controller. So, U.3 only requires 1 backplane, 1 mid-plane, and 1 controller, supporting all these drives in the same slot.

Tri-mode controllers alone are not enough, here the disc backplanes also come into play.

For the perfect Tri-Mode operation, system needs to have

• One Backplane

• One connector

• Less high-speed lanes to backplane

• One Mid-plane

• Tri-mode Expander

• One HBA / RAID Controller

Tri-Mode controllers should be PCIe 4.0 and it means that the slot and our disks in the server should be 24G.

On a PCIe 3.0 server, you can use all disk types at the same time with tri-mode controls and U.2 and/or U.3 disk backplane, of course, it will work at PCIe 3.0 and U.2 speed in terms of performance

Storage Today vs Tri-mode

Tri-Mode technology brings a wealth of options and flexibility using of SAS devices, Serial ATA (SATA) II and SATA III devices, and PCIe (NVMe) within the same storage infrastructure.

The Tri-Mode controller, for example, Broadcom 9600 Series provides

• SAS Serial SCSI Protocol (SSP), which enables communication with other SAS devices
•  SATA III, which enables communication with other SATA II and SATA III devices
•  Serial Management Protocol (SMP), which communicates the topology management information directly with an attached SAS expander device
•  Serial Tunneling Protocol (STP), which enables communication with a SATA III device through an attached expander
• NVMe, which accesses storage media that is attached by a PCIe bus. Both NVMe SGL and PRP drives are supported. The controller firmware does not use the SGL capabilities of the drives. I/Os are issued based on the PRP format.

Storage Today

Tri-mode storage