Kioxia CM6 low write speeds

[ycp]

Hello,
I have a few 30TB Kioxia CM6 ssds the read intensive ones.
The read speeds in CrystalDiskMark are around 3200Mbps.
But the write speeds are around 1100Mbps.
In the official documentation the drives are rated for much more.
What could be the problem?

 

[mrpasc]

As you did not provide any system information just one first guess: not enough cooling so they start to throttle.

 

[ycp]

They are installed in a Supermicro SuperServer 2029U-TN24R4T with Dual Xeon Silver 4116 cpus and 64gb of memory.

There are only 3 CM6 ssds in the server. No other NVMe drives are installed.

 

[ycp]

The Drive temps are not going over 50c during heavy write workloads

 

[uldise]

how are the drives connected?
i see some PCIe switched used in system. can you try different ports? i'm not sure how backplane are connected to the mobo.

 

[ycp]

The connections are confusing for me also. The backplanes are connected to some special supermicro pice cards.
They are not raid cards or HBA's thats for sure.

 

[uldise]

if you wanna just test a drive, can you connect it to PCIe with adapter just to see how it works?

 

[uldise]

your drives are PCIe 4.0, while your server is PCIe 3.0 only, so you will never reach drive full potential..

 

[ycp]

I understand that the drive are PCIe 4.0 but i am not looking for the full potential of PCIe 4.0.
The problem is that according to the datasheet of the drives i am no where close to the max PCIe 3.0 rated write speeds of the drive.
Maybe the server is the bottleneck.
I dont have a PCIe adapter. I will have to order one to test this out.

 

[ano]

try format namespace with ses=1 or 2, but its still kinda weird

 

[ycp]

i am running windows server

 

[ano]

screenshots?

 

[ycp]

Screenshots are attached
If you want me to do other tests let me know.

 

[ano]

thoose make 0 sense more 4KB than 1MB

 

[ycp]

yes it makes no sense.
Any ideas?

 

[ano]

try AS SSD benchmark, or other benchmark, but something is weird here.

 

[uldise]

and/or try some Linux live version and test with fio..

 

[111alan]

For this specific model, try adding more threads to the sequential tests. For example, Q4T4 or Q8T8.

 

[ano]

it should work regardless really though, but fio the device directly from linux