Question Slow transfer speed withing same nvme drive

delicatoboll

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Got a WD SN750 1TB m.2 drive installed. It's on the correct settings. Crystaldiskmark shows reasonable results.
But, I'm having slow transfers in real life usage. For instance, if I copy a folder and transfer it to somewhere else on the drive, it takes long time to perform (speeds like 3-5MB/s are not unusual). Same for compressing/extracting files. And another example when I empty the recycle bin, it takes forever.

Help appreciated to solve this.
 

delicatoboll

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how much free space on the nvme?

It might be because of how ssd record the data and have to move an entire block to add just a little info. It can't just put the info into an area without moving all the info in that area so it can rewrite it all.

have you run https://support.wdc.com/downloads.aspx?p=279 to check drives health?
Free space is 92.9%.
Drive is new (health 100% according to WD Dashboard) and I have a clean Windows 10 install with the latest Chipset driver.
 

Colif

Win 10 Master
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file size plays a part, lots of really small files will slow it down

You need to understand the difference between copying and moving files on the SAME hard drive. A COPY requires that the original file be read, and then re-written to the new location. So the same data has to be handled twice, and the overall speed of the operation will be approximately half the speed of the drive.

A MOVE of a file to another location on the same drive does NOT move the file! The entire file itself is left alone. ONLY the Directory data for that file is copied from one folder to another. The file now is in the new folder, but the actual data never moved. So this is "almost instantaneous".
 

delicatoboll

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file size plays a part, lots of really small files will slow it down



Al right.
So I tried this; I compressed large number of files (did not go so fast) into one file of approx. 10GB in size. I copied the compressed file and pasted it to another place in the drive. The transfer speed got faster (about 1Gb/s). But, advertised speed of the m.2 drive is 3000MB/s in write, so I still should get approx. 3GB/s? Right?
 

delicatoboll

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Not when reading/writing within the same drive.

Please give us details about the rest of the parts in this system.
ASUS Z390-A Prime
i7-8700k
DDR4 2x8 GB
GPU GTX 1060
2nd M.2 Samsung 960 Evo 250GB

I did a clean install of Windows now. Performed benchmarks, Write and Read are as they should (3400/3000).

However, the random IOPS are low.

Advertised: 515000 / 560000
My results: 319000 / 241000
 

Colif

Win 10 Master
Moderator
However, the random IOPS are low.

Advertised: 515000 / 560000
My results: 319000 / 241000
how are you measuring this? what app?


What speed do you get transferring data to 2nd nvme?

That 3k tfr speed is over pcie, not on the nvme itself.

On the NVME, it has to juggle the data being moved as well as the data it has to move to create room for the data you are moving. The cache is only so big. I don't know about WD nvme but on Samsung, the size of the cache depends on how much free space is on the drive itself, the more you use, the less it can run at full speed before it hits its limit. Only my drive it started as 41gb of space before it slows down.
 

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