Question Low SSD write speed when downloading via Steam

[qwertynosik]

Good afternoon! Could anyone explain to me, why I have low write speed with SSD when I am downloading a game in Steam?

I have an internet connection with stable speed of 1500+ Mbits/s. So, since I have an SSD, I expect a downloading speed of the game via Steam of about 1500/8 ~ 190 MBytes/s. However, when I download a game, the downloading speed is limited by disk write speed of something like 160-170 MBytes/s. I attach an example of a downloading, so it is clear that disk write speed remains the same since the very beginning of downloading, and is about 160-170 MBytes/s. Downloading speed in turn starts at about 10 MBytes, and then steadily increases right up to disk write speed of 160-170 MBytes. So, it looks like the SSD is a real bottleneck, and if the SSD speed were more than 160 Mbytes, I would have a downloading speed of 190 MBytes as it was expected.

I checked my SSD with CrystalDiskMark, and it seems that 170 MBytes is the same as write speed in Random 4KiB Queue 1 Thread 1 mode. So, why is the disk write speed in Steam limited by these 170 MBytes? Why is it that far from advertised 3000 MBytes/s write speed? Can I somehow increase it?

I cannot insert the images for some reason, here are the links

https://imgur.com/Wijki1J

View: https://imgur.com/Wijki1J

https://imgur.com/azq8w0f

View: https://imgur.com/azq8w0f

 

[ak47jar3d]

That seems fine. It can hit 3000, but certain qdefs that can bog it down....

 

[qwertynosik]

That seems fine. It can hit 3000, but certain qdefs that can bog it down....

Well, theoretically, yes, it can reach 3000. But if it reaches this speed only in synthetic tests and benchmarks, and real speed is like 20 times slower, why should I be okay with this?

When I transfer files from this SSD to another similar SSD (with read/write speed of 3000+ as well), the real transfer speed is much lower than 3000 as well. It barely reaches 1500, and usually is about 1000. Instead of advertised 3000.

Ok, you can say that the SSD is not empty, and the speed decreases with occupied volume of SSD, and also when I transfer files, they have different sizes and structure, so it will be slower for a lot of small files etc. But ok, I can accept 1-1.5 GBps for transfer speed inside the SSD and between SSDs. But why do I have such a slow speed when I download the game from Steam? As I said, Internet speed is higher than actual downloading speed, so it looks like it is limited by SSD and not the Internet connection.

 

[USAFRet]

That 168MB

Well, theoretically, yes, it can reach 3000. But if it reaches this speed only in synthetic tests and benchmarks, and real speed is like 20 times slower, why should I be okay with this?

When I transfer files from this SSD to another similar SSD (with read/write speed of 3000+ as well), the real transfer speed is much lower than 3000 as well. It barely reaches 1500, and usually is about 1000. Instead of advertised 3000.

Ok, you can say that the SSD is not empty, and the speed decreases with occupied volume of SSD, and also when I transfer files, they have different sizes and structure, so it will be slower for a lot of small files etc. But ok, I can accept 1-1.5 GBps for transfer speed inside the SSD and between SSDs. But why do I have such a slow speed when I download the game from Steam? As I said, Internet speed is higher than actual downloading speed, so it looks like it is limited by SSD and not the Internet connection.

"Internet speed" is vastly slower than your drive speed.

Gigabit internet or LAN speed is slower than even a spinning HDD.
Seriously.

 

[kerberos_20]

downlaoding from steam is pretty much sequential, that is Q1T1, no clue how big network packets are, should be bigger than 4k blocks...even torrents goes with 4MB blocks
sooo basicly in crystal disk mark, go to settings -> queues and threads and change it to 1/1 for all tests

then you can see what your drive is capable of with steam

there isnt much you can do about it...maybe ram cache for writes would help...other than that steam could use ram buffer and than flush it with multiple threads to utilize nvme better...but thats a whisful thinking

 

[qwertynosik]

I didn't really get it.

That 168MB

What do you mean? What is 160MB?

"Internet speed" is vastly slower than your drive speed.

Well, it should be slower. My internet is 1500-2000 Mbps, so it is 190-250 MBps. My SSD write speed should be 3000 MBps. Ten times faster. So that is why I expect the internet to be the bottleneck, and that is why I expect downloading speed of 190 MBps in Steam. Because the connection is stable, and it never goes under 1500 Mbps. And I don't use any programs in background. But for some reason, my downloading speed is less than 170 MBps. And if you take a look at the graph, it really looks like it is limited by the SSD write speed. Because the SSD speed is almost constant since the very beginning, and it is only 170 MBps.

 

[USAFRet]

The "168MBs" I mentioned is what is showing in your Steam screencap.

168 * 8 = 1,344Mbps.
Slightly less than but in the ballpark of your supposed "1500-2000 Mbps ".

Steam can't necessarily fill up your pipe all the time.


I'm not seeing an issue.

 

[qwertynosik]

then you can see what your drive is capable of with steam

there isnt much you can do about it...maybe ram cache for writes would help...other than that steam could use ram buffer and than flush it with multiple threads to utilize nvme better...but thats a whisful thinking

I checked the speed for Sequential Q1T1 mode for package sizes from 4Kib to 8MB. So, it is clear that for small packages you have slower speed, but anyway. I have the following write speed:

Package size	Write speed
4K	160 MBps
512K	2800 MBps
4MB	3100 MBps
8MB	3100 MBps

So, if the package size is bigger than 4 Kb, then write speed should be higher than 170 MBps

 

[qwertynosik]

The "168MBs" I mentioned is what is showing in your Steam screencap.

168 * 8 = 1,344Mbps.
Slightly less than but in the ballpark of your supposed "1500-2000 Mbps ".

Steam can't necessarily fill up your pipe all the time.


I'm not seeing an issue.

Ok. I am going to connect the internet via cable in the end of the month, so it will give me internet speed of at least 5 Gbps. I will check Steam with this speed, and then we will see the result. If it is not around 600 MBps, there is a problem somewhere.

 

[USAFRet]

Ok. I am going to connect the internet via cable in the end of the month, so it will give me internet speed of at least 5 Gbps. I will check Steam with this speed, and then we will see the result. If it is not around 600 MBps, there is a problem somewhere.

Again, Steam is not necessarily going to fill your pipe to its full capacity.

And currently, your PC is connected to your router via WiFi?