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Slow Write Speeds on NVME Cache on 10Gbps Network


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Hello!

I need help because I am having difficulty achiving the full speeds of my network and NVME drives using UNRAID.

I have the following:
- Windows 10 Client with a Samsung 980 PRO 1TB NVME

- UNRAID server with a Corsair MP600 1TB NVME Cache drive and DirectIO enabled

- 10Gbps Ubiquiti Network with both client and server connected on the same switch, and them and the switch have JUMBO FRAMES enabled at 9014 bytes.

- CAT8 cables running to the devices with no more than 6-8 meters on each client

 

1º Problem: I am unable to get 10gbps connection to the UNRAID server, max is about 6.7Gbps, as stated in the image bellow:
speed.thumb.PNG.02ef6d7ee50b923ae822d239e0cd2833.PNG

 

Anyone knows what may be happening?

 

2º Problem: Altough when copying a file from UNRAID to WINDOWS is stable and almost near the speed of the test, at about 777MBps (6.07gbps)

UNRAID_WIN_DIRECT.PNG.3cbeb9ebb8d0bfd2846559e2c5974f67.PNG

 

When copying from my computer to the UNRAID cache, the speed is very inconsistent (sometimes worse than the image) and maxes around 500MBps

WIN_UNRAID_DIRECT.PNG.0b07ca1afc1d994fafda365b17147592.PNG

 

The disk being used as cache is capable of well over 10gpbs speeds when writing as can be seen here https://ssd.userbenchmark.com/SpeedTest/843047/Force-MP600

 

What may be wrongly configured to cause this? Enabling DirectIO did not improve write speeds, but increased drasticly the READ speeds, and that goes against the info on the toggle.

 

Thanks for the help

 

 

Edited by TZodiacK
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  • 1 year later...

Hi, same problem here... stuck at 160MB/s when i copy from PC to Unraid cache SSD...

image.png.4b1757d8228ba4c22021ba1ee976fc42.png

From Unraid cache SSD to PC i have about 700MB/s stable... (with 10Gb ethernet tx401 tp link)

image.png.733ce60ca2586f4fbdf5c49f8b100b56.png

My unraid build has 2 SSD 980 PRO 1TB in one pool cache raid 1 with encryption

CPU is ryzen 9 5950X with 32BG RAM ECC

I tried direct write to /mnt/cache but it is exactly the same !

sad...

Edited by Bender Seb
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If i put MTU=9000 on both sides; it is better...

 

image.png.d4c36386c7680e773364b7abf1b1adbf.png

image.png.f40fca07e4d2e906173d8d8fc35e9ea4.png

SMB multichannel allowed full speed for transfert from unraid to PC, but in the other direction (PC to unraid) there is only one channel... so packet size matters i suppose...

MTU=9000 here

But my applications are not reachable from outside of my network behind my commercial router...

iperf indicates full speed with 5 parallel streams but can't offer more 2 Gb/s with just one stream...

 

So it is a network bottleneck...

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