X399 Raid low performance

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   HI,

Last week I decided to build a NVME raid of 3 drives and the result is subpar.

The system is:
Taichi x399. bios 3.30
Threadripper 1900x 
32 GB g-skill at 2400 
3 X Samsung 960 evo.

I performed single drive bench in ahci reaching the advertised speed from the drive. I enable the raid controller and do a single drive JBOD my performance on read drop to 2100 instead of the normal 3k. Write stay the same. If I do a 2 drives bench I have the normal 3.6K write and 4.2k read. If I do 3 drives I get 5.4K write and 6.2 read.

As you can see everything is consistent in number of drives and performance except I miss 1k in read for each drive in raid mode.

Any one got a idea why I have 3k read performance missing in my raid ?

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Pape Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 26 Nov 2017 Status: Offline Points: 33	Post Options Post Reply Quote Pape Report Post Thanks(0) Quote Reply Topic: X399 Raid low performance Posted: 29 Dec 2018 at 2:17am
	HI, Last week I decided to build a NVME raid of 3 drives and the result is subpar. The system is: Taichi x399. bios 3.30 Threadripper 1900x 32 GB g-skill at 2400 3 X Samsung 960 evo. I performed single drive bench in ahci reaching the advertised speed from the drive. I enable the raid controller and do a single drive JBOD my performance on read drop to 2100 instead of the normal 3k. Write stay the same. If I do a 2 drives bench I have the normal 3.6K write and 4.2k read. If I do 3 drives I get 5.4K write and 6.2 read. As you can see everything is consistent in number of drives and performance except I miss 1k in read for each drive in raid mode. Any one got a idea why I have 3k read performance missing in my raid ?

Pape Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 26 Nov 2017 Status: Offline Points: 33	Post Options Post Reply Quote Pape Report Post Thanks(0) Quote Reply Posted: 29 Dec 2018 at 3:13am
	Decided to test all 3 drives in AHCI and found out that slots 2 & 3 bench at 2.5K read. Slot 1 reach the 3.1K, this is in specs. According to Samsung Magician all 3 drives are set to PCIe Gen 3 at 4X in good condition running the latest Firmware. Will need to go dig down in the hardware.... The question continue to hold: any of you have a clue what can cause this ?