NVME Breakout PLX Switch PCI-E adapter

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Blinky 42

Active Member
Aug 6, 2015
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PA, USA
Interesting .... Looks the same as this one NVMe PLX adapter card PCIe3.0 X16 to 8-port built-in 8643 interface to U.2 NVME | eBay and cheaper PLX NVMe adapter card PCIe3.0 X16 to 8-port built-in 8643 interface to U.2 NVME | eBay
All are probably this LRNV9349-8I
The Linkreal site lists 3 versions of the card however

There seem to be a bunch of the same generic boards w/PLX chip + 8x SFF-8643 all over the china hw sites. Probably not bad price if it is the real PLX chip. The main difference with the SM part would be it doesn't have oculink connectors.
 

RedneckBob

New Member
Dec 5, 2016
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Anyone familiar with this product

PLX NVMe adapter card PCIe3.0 X16 to 8-port built-in 8643 interface to U.2 NVME | eBay

I am curious if this is a cheaper alternative to the supermicro oculink AOC-SLG3-8E2P.
I have a couple NVMe 2.5" u.2 drives and so I'm searching for a controller. Super curious about these...one thing I did notice is these Linkreal adapters have 2x the drive bandwidth than available PCIe bandwidth.

For example, here they are stuffing 4 PCIe x4 3.0 channels through 2 PCIe x4 3.0 channels.
These adapters are starting to popup more often so I'm surprised no one has done solid round of testing or benchmarking.
 

digity

Member
Jun 3, 2017
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I know this is super late, but I have a Linkreal LRNV9349-8I (PLX8749 chipset, 8 port, PCI-e 3.0 x16) and Linkreal LRNV9347-4I (PLX8747 chipset, 4 port, PCI-e 3.0 x16). In my simple tests so far these cards each seem to max out at ~3500 MB/s read and write. Based on the results below, do these cards truly max out at 3500 MB/s (essentially x4) despite being x16 (14000 MB/s possible) or do I need to run benchmarks differently? Or is there another explanation?


TrueNAS Core 13.0-U5.1
MSI Z590-A PRO mobo, i7-11700k 8c/16t CPU, 16 GB DDR4 RAM
Micron 9200 Max 1.6 TB U.2 NVMe SSD (3500/1900 MB/s rated)
dd ... bs=128k count=800k
1x VDEV = 2486 MB/s (R), 3358 MB/s (W)
2x VDEVs = 3579 MB/s (R), 3264 MB/s (W)
3x VDEVs = 3579 MB/s (R), 3344 MB/s (W)
4x VDEVs = 3579 MB/s (R), 3329 MB/s (W)
CPU percentage reached 26% at it's highest during these tests
VDEV consists of one (1) U.2 SSD drive


P.S. - I tested 3x M.2 SSDs (via the 3 built-in M.2 slots on mobo) the same way as the U.2 SSDs and essentially reached 5000 MB/s read & write with 3 VDEVs (CPU percentage reached 50% at it's highest during these tests)
 

digity

Member
Jun 3, 2017
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Just noticed something on the link and speed of the Linkreal card itself. "pciconf -lvc" verifies all the U.2 drives are running at their full link and speed "link x4(x) speed 8.0(8.0)", essentially PCI-e 3.0 x4, but the card itself says "link x4(x16) speed 8.0(8.0)" which indicates it's running at x4 too instead of it's capable x16. I guess this would explain why I'm maxed at 3500 MB/s...? If so, any ideas how to get it to run at x16?

Here's the output from pciconf (card portion):

Code:
pcib4@pci0:3:0:0:       class=0x060400 rev=0xca hdr=0x01 vendor=0x10b5 device=0x8749 subvendor=0x10b5 subdevice=0x8749
    vendor     = 'PLX Technology, Inc.'
    device     = 'PEX 8749 48-Lane, 18-Port PCI Express Gen 3 (8.0 GT/s) Multi-Root Switch with DMA'
    class      = bridge
    subclass   = PCI-PCI
    cap 01[40] = powerspec 3  supports D0 D3  current D0
    cap 05[48] = MSI supports 8 messages, 64 bit, vector masks
    cap 10[68] = PCI-Express 2 upstream port max data 256(512) RO NS
                 max read 128
                 link x4(x16) speed 8.0(8.0) ASPM disabled(L1)
    cap 0d[a4] = PCI Bridge subvendor=0x10b5 subdevice=0x8749
    ecap 0003[100] = Serial 1 ca870010b5df0e00
    ecap 0001[fb4] = AER 1 0 fatal 0 non-fatal 1 corrected
    ecap 0004[138] = Power Budgeting 1
    ecap 0019[10c] = PCIe Sec 1 lane errors 0
    ecap 0002[148] = VC 1 max VC1 lowpri VC0-VC1
    ecap 0012[e00] = Multicast 1
    ecap 0018[b00] = LTR 1
    ecap 000b[b70] = Vendor [1] ID 0001 Rev 0 Length 16
 

TRACKER

Active Member
Jan 14, 2019
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short answer: you have to replace the mobo :)
long answer: your mobo has 2 x PCIe x16 according the specs: one of the slots is x16 and one x4.
you did not mention the graphics card you use, but i assume you use x16 slot for it.
If you move the GPU to x4 slot and use NVMe card to x16, then maybe you would have better results.