Transfer rate decrease with multiple drives?

bruNOshoes

New Member
Hello people, I hope you are keeping good and safe.
I'm experiencing a huge transfer speed drop down on nearly every ssd,hdd that I have, and I'm wondering if anyone can give me a hint of what could be.

I'm uploading several screenshoots that shoows how it starts with a proper write speed and you will notice how it drops to 70ish MBPS after a while.

I tried in many different drives and the result is always the same.
to
First Screenshoots is transfering from a SSD Samsung 860 QVO to an external HDD WD. It started 180 MPB and you can see droped to 70.

Second screenshoot is transfering from a SSD WD BLUE to a Samsung860 QVO, again starts at 480ish MBP and drop to 70. (The SSD WD Blue is an external disk connected via USB C)

Third screenshoots shows a transfer from my internal SSD'd both are Samnsung 860. Again, from 480ish drops after a while to 70.

I did tried with more several dist and result is always the same.

My pc is an i9 9900k , 64 GB ram and rtx 2070.

Any help would be appreciated! Thanks!
 

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OmniDyne

Active Member
None of that is abnormal; the QVO line is not geared for performance, at all.

First Screenshoots is transfering from a SSD Samsung 860 QVO to an external HDD WD. It started 180 MPB and you can see droped to 70
The result of a few moments of SLC cache bursting. 70MB/s is your direct-from-QLC NAND read speed. This speed will vary greatly depending on how full the drive is and what workload the drive is under.
Second screenshoot is transfering from a SSD WD BLUE to a Samsung860 QVO, again starts at 480ish MBP and drop to 70. (The SSD WD Blue is an external disk connected via USB C)
480MB/s is your SLC cache speed burst. This time, 70MB/s is your direct-to-QLC write speed.
Third screenshoots shows a transfer from my internal SSD'd both are Samnsung 860. Again, from 480ish drops after a while to 70.
Again, limitations of pseudo SLC caching and QLC NAND.

All SSDs experience this. If you want faster transfers you will need to purchase higher-end drives that utilize 3D TLC NAND or MLC NAND. Samsung Evo or Pro lines, for example.
 
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beers

Moderator
Staff member
Three factors.

1) The progress transfer bar isn't always accurate, with buffering techniques it will overstate the transfer rate initially in many cases.
2) Writing from SSD to mechanical can slow down as the inner portion of a mechanical disk is inherently slower due to physics
3) Writing from anything to SSD such as the RAM buffer in your case will exhibit #1, but also the QVO has slow write performance to the QLC NAND after its buffer has been exhausted.
 

OmniDyne

Active Member
I see. I reckon the WD BLUE 3d NAND would also do the job?
Are you talking about the Western Digital Blue 3D SATA SSD? If so, it would likely be over twice as fast as the QVO, but it's not really meant for those workloads.

You need to take into consideration endurance as well. How often are these drives being subjected to these types of workloads? How much are you writing to these SSDs per day? Per month?

SSD warranties work a little different than typical consumer HDD warranties. Manufacturers specify a TBW endurance rating; the amount written to the SSD during the warranty period. The QVO has something like 360 TBW for 3 or 5 years. That means Samsung guarantees operation within the warranty as long as 360 terabytes isn't written to the drive. It's possible the drive will fail when and if you breach this threshold.

360 TBW is quite low for an SSD. High end and mid-range SSDs are given upwards of 2,000 TBW endurance ratings, for good reason.

If you're writing hundreds of gigabytes per day, you need to consider spending more on a more appropriate SSD.
 

bruNOshoes

New Member
Are you talking about the Western Digital Blue 3D SATA SSD? If so, it would likely be over twice as fast as the QVO, but it's not really meant for those workloads.

You need to take into consideration endurance as well. How often are these drives being subjected to these types of workloads? How much are you writing to these SSDs per day? Per month?

SSD warranties work a little different than typical consumer HDD warranties. Manufacturers specify a TBW endurance rating; the amount written to the SSD during the warranty period. The QVO has something like 360 TBW for 3 or 5 years. That means Samsung guarantees operation within the warranty as long as 360 terabytes isn't written to the drive. It's possible the drive will fail when and if you breach this threshold.

360 TBW is quite low for an SSD. High end and mid-range SSDs are given upwards of 2,000 TBW endurance ratings, for good reason.

If you're writing hundreds of gigabytes per day, you need to consider spending more on a more appropriate SSD.

This is a lot of new and valuable information. Thanks you very much. I reckon I would transfer close to 2 TB a month of data into the main QVO. I have a second one which I use for the cache files so I rerckon that one has less use. Anyhow if 360 TB is their count I am covered for at least a few more years ( if my math are good)
Now my issue would be indeed in that massive drop down of transfer speed rate. Something curious that I noticed is that the longer the PC is "ON" the longerr it transfers at 480 MB/s before it drops to 70 MB/s. For example, if I just turrned on the pc and start transfering a file, it will drrop to 70 in the first minute, on the other hand I had moments where the pc was on from long ago and it would transfer a full 500 GB SDD at 480 MB/s constant. Would you know why can that be?

If I would aim to buy a SSD whith better and more stable transfer rates, how would I spot one?

Thanks again for your time!

PS: Just to add, Idk if would be the same issue, but even downloading from a SD card into the laptop SD reader, the same occurs. I have a 300MB sd card, which starts with that nice burst of 300 MB/s and again, afterr a while, the transferr speed goes down to 70MB.
Now the werid part of this scenario is that from the SD card I'm transfering to my NVMe M2 Samsung 970 EVO Plus, which is my main SSD, supossed to transfer 3500 MB/s.. so no QVO involved in this operatioin, yet results are the same.. I thought was worth mentioning it.
 

beers

Moderator
Staff member
from the SD card I'm transfering to my NVMe M2 Samsung 970 EVO Plus, which is my main SSD, supossed to transfer 3500 MB/s
SD cards are a lot slower than drives made specifically as SSDs. Nothing has infinite bandwidth, each storage mechanism has its own physical properties that influence transfer rate.
 

bruNOshoes

New Member
I know that, but if you read my previous post, you will notice we are speaking of a SD card with a 300 MB/s writing speed. I know it doesnt fail the card as I use it to record 4K video and I can record up to 2hs without interuptions, hence that writing speed is okay... so why when transfering to the EVO 970 NVME it also drops to 70?

Here I did a few more test and all of them arre very interersting... and frustrating.




Test 1: In this case I thought I should try my maiun NVME m2 Samsung EVO 970. Which has a max speed of 3500 MBs. I have this drive in my pc among with two QVO previously mentioned.

Here comes the catch again... when transfering from my QVO to the EVO 970 it also starts sweet constant rate of 550 mb, after 2 minutes, drops down to 70MB again.



Test 2: Just to make sure, I tried also from a WD BLUE SSD to my 970 EVO and the samme occurs. Now I know its impossible the write speed of a 970 EVO can be 70 MB... this just doesnt sounds okay. And I know its not the WD BLUE as I use that to record 4 K video, and I can record continuously at a rate of 240 MBs until I fill that disk... so it has to be something else.



Test 3: I transfered to my 970 EVO from my Sandisk extreme pro uhs-II (300 MB/s) a card I use to record also, 4K video and which I can record non stop until is finished... and again, we start with a nice transfer of 280 MB and afterr 1 or 2 minutes, back to 70 MB...



Test 4: here comes the most interesting part.. I have a second laptop from 2014, i5 8gb ram, and I upgraded it with a WD Blue SSD... when transferring into that laptop there is no transfer speed drop at all.... hence my reason to belive it has nothing to do with drives as I tried, HDD, SSD, NVME, and SD CARDS, all giving the exact same results and transfer drops go exactly to 70 MB/s....



Thanks again!
 

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