Question Sata SSD in external enclosure is not that fast, what's the bottleneck here?

Jorge_acosta

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Hello, i have a 2tb crucial ssd (Ct2000mx500ssd1) that I intend on using it as a storage solution for when i travel, i do fishing videos for youtube, and sometines i travel for fishing, so i do a week of fishing everyday and each day I end up with about 150 GB of video footage.... So what i do is at the end of the day before going to sleep I have to transfer all my camera files from a bunch of micro SD cards to an external HDD... this is usually a long and tedious process at transfer sepeeds of 80 MB/s so i decided to upgrade to an SSD to make this process faster... so i bought the 2TB ssd and an external enclosure (UGREEN 3.1 gen 2 usb external enclosure) thinking this should be faster right? it's an ssd... SSDs are faster than HDDs... but now i am getting 38 MB/s transfer speeds... So what gives? what's the problem here? how can i find out where the bottleneck is? What kind of transfer speeds should i expect by using an external SSD?

Hope you guys can help me
 

neojack

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the bottleneck is probably the SD card and/or the card reader wich is probably USB2, right ?
also make sure to use USB ports that are away from each other. USB ports close from each other are often shared on the same controller, and transfert speed between ports on the same controler is divided by 2.
 

USAFRet

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Copying from a microSD card to <whatever>...the SD card is almost certainly the limiting factor.

Speed in this is dictated by the slowest device in the chain.
Here, the SD card. After that, the USB interface.
 

Jorge_acosta

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the bottleneck is probably the SD card and/or the card reader wich is probably USB2, right ?
also make sure to use USB ports that are away from each other. USB ports close from each other are often shared on the same controller, and transfert speed between ports on the same controler is divided by 2.
hmmm the SD card reader is usb 3.1 too... with that same card reader i get 80 MB/s when copying to my external HDD... i will check with using a different usb port, becouse last time i was using usb ports that where next to eachother, thank you!
 

Jorge_acosta

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Copying from a microSD card to <whatever>...the SD card is almost certainly the limiting factor.

Speed in this is dictated by the slowest device in the chain.
Here, the SD card. After that, the USB interface.
Well i forgot to mention that since i record my footage at 2.7 k resolution the Micro SD cards that i use are SanDisk Extreme wich are rated at 150 MB/s read speed and 90 MB/s write speed... So it shouldn't be the micro SD...
 
If you get 80mb/s writing to a HDD and only 38MB/s to a ssd,
I have to conclude that the problem is the ssd.
What is the make/model of the ssd?
Yes, ssd devices are truly fast compared to a HDD when reading.
But, writing is another story.
It depends on the ssd and the type of nand chips it uses.
Once whatever buffer the ssd has gets filled, you are reduced to nand block write speeds.
Samsung QVO will not be as fast as the EVO and EVO pro units for example.
Other lesser devices could be worse.
 

Jorge_acosta

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If you get 80mb/s writing to a HDD and only 38MB/s to a ssd,
I have to conclude that the problem is the ssd.
What is the make/model of the ssd?
Yes, ssd devices are truly fast compared to a HDD when reading.
But, writing is another story.
It depends on the ssd and the type of nand chips it uses.
Once whatever buffer the ssd has gets filled, you are reduced to nand block write speeds.
Samsung QVO will not be as fast as the EVO and EVO pro units for example.
Other lesser devices could be worse.
It's a 2tb crucial ssd MX500 ( https://www.newegg.com/crucial-mx500-1tb/p/N82E16820156174# )
 
Your MX500 is one of the better ones.
The biggest benefit in performance with a ssd is minimal latency.
Some 40x better than a HDD.
This is a major benefit to random access.
For the sequential operation that you are doing, that benefit is minimal.
The MX500 is primarily made up of TLC nand blocks. TLC is slower than MLC or SLC but it is much cheaper to make. To compensate, the MX500 has a SLC buffer which can take faster writes.
I do not know the size of that buffer.
You are hitting the ssd with, I presume, large blocks of data very quickly.
Once the SLC buffer is overwhelmed, the drive must revert to slower writes.

Writing to a HDD sequentially has a small latency penalty, but once the write starts, it proceeds at rotational speeds.

Another problem arises if the ssd is near full.
Then you may need to do several read/write operations to accumulate free nand blocks to do the write.

The nand blocks in a ssd have a limited number of writes.
Is it possible that you have been hitting this ssd with so much data that the slc buffer or the tlc nand is losing the capability to do writes.
I think crucial has some utilities that would be worth running.

What to do??

For now, go back to the HDD device and 80MB/s

A HDD should be able to do sustained writes on the order of 120MB/s
To do better, look at the usb controller or the flash device performance.
 

Jorge_acosta

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Well the ssd is brand new, just did some file transfers to see what speed i got... So i go back to the HDD then... dang it... well i guess i will put the mx500 in my desktop then. Thank you man!
 

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