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Question Will this SSD work ?!

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Feb 20, 2020
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Your OS will cache writes in RAM but if you're going at a steady pace the bottleneck is the drive ultimately. Likewise, certain transfers do have I/O overhead (esp. many small files), but generally speaking the limit will be the drive and not the CPU's overhead. Exception would be with compression of course which is RAM- and CPU-heavy, backup software generally does use moderate compression.
Thankyou so much for your help. Also may I ask how did you know Whiskey Lake-U supports only x2 PCIe 3.0 for its SSD M.2 socket. Are there sources that I can know more regarding this type of information?
 

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It's possible for the Key M M.2 socket to be x2 or x4 on them. Usually I research the specific motherboard, in this case I couldn't find anything that suggested x4 support. For example on this datasheet under expansion slot it's limited to PCIe x2 for the M key (different board, but Whiskey Lake-U).
 
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It's possible for the Key M M.2 socket to be x2 or x4 on them. Usually I research the specific motherboard, in this case I couldn't find anything that suggested x4 support. For example on this datasheet under expansion slot it's limited to PCIe x2 for the M key (different board, but Whiskey Lake-U).
Also I want to ask how come when transferring files to the laptop ssd, at first it starts out crazy then it drastically drops to like USB drive speeds? Shouldn't the speeds be constant, straight line?
 

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Also I want to ask how come when transferring files to the laptop ssd, at first it starts out crazy then it drastically drops to like USB drive speeds? Shouldn't the speeds be constant, straight line?
There may be some caching in RAM, depending, but generally the average speed is determined by the source and/or destination. If you're reading from SATA you will always be limited to 500 MB/s or so even if writing to NVMe. If you're reading from USB it could be higher or lower (5 Gbps or 10 Gbps generally, the latter for NVMe in enclosure). And the destination drive has SLC caching which is limited in size, after it is exhausted you will drop down to TLC/QLC speeds which are slower. The exact speeds of which depend on the drive, drive capacity, SLC cache design, etc. Generally speaking the best outcome would be probably 900 MB/s or so with a 10 Gbps enclosure and NVMe drive, writing to an internal NVMe drive that has a fast base TLC speed. Although if the drive is internally copying to itself it may be faster than this.
 
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There may be some caching in RAM, depending, but generally the average speed is determined by the source and/or destination. If you're reading from SATA you will always be limited to 500 MB/s or so even if writing to NVMe. If you're reading from USB it could be higher or lower (5 Gbps or 10 Gbps generally, the latter for NVMe in enclosure). And the destination drive has SLC caching which is limited in size, after it is exhausted you will drop down to TLC/QLC speeds which are slower. The exact speeds of which depend on the drive, drive capacity, SLC cache design, etc. Generally speaking the best outcome would be probably 900 MB/s or so with a 10 Gbps enclosure and NVMe drive, writing to an internal NVMe drive that has a fast base TLC speed. Although if the drive is internally copying to itself it may be faster than this.
I am copying from USB drive to laptop ssd. The ssd is WD SN520 PCIE x2. I am copying a 50 GB file to laptop ssd. Are there ways to make the transfer speed constant and high?
 

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I am copying from USB drive to laptop ssd. The ssd is WD SN520 PCIE x2. I am copying a 50 GB file to laptop ssd. Are there ways to make the transfer speed constant and high?
On the source end, you're limited by USB speeds. This depends on the speed of the device and the port. Correct me if I'm wrong, but the fastest port on there is USB3.1 Gen1 which would be (5)(8b/10b)(0.9) = ~460 MB/s. So you'll always be limited by that.
 
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On the source end, you're limited by USB speeds. This depends on the speed of the device and the port. Correct me if I'm wrong, but the fastest port on there is USB3.1 Gen1 which would be (5)(8b/10b)(0.9) = ~460 MB/s. So you'll always be limited by that.
I have no knowledge on this. I trust you're 100% correct. Please correct me if I'm wrong, so when copying files from USB drive to laptop ssd, the MAXIMUM write speed of the SSD is determined by the PORT of the SOURCE, in this case a USB 3.1 Gen 1 drive ?!
 

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I have no knowledge on this. I trust you're 100% correct. Please correct me if I'm wrong, so when copying files from USB drive to laptop ssd, the MAXIMUM write speed of the SSD is determined by the PORT of the SOURCE, in this case a USB 3.1 Gen 1 drive ?!
Yes, I mean the port is the limitation assuming the device/drive is as fast or faster. If your source is a fast SATA SSD, for example, it will be bottlenecked by USB 3.1 Gen 1. The internal drive is likewise bottlenecked by the port bandwidth/speed. There's no real escaping that.
 
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Yes, I mean the port is the limitation assuming the device/drive is as fast or faster. If your source is a fast SATA SSD, for example, it will be bottlenecked by USB 3.1 Gen 1. The internal drive is likewise bottlenecked by the port bandwidth/speed. There's no real escaping that.
Thankyou very much. What role does the USB drive's READ speed play when copying files from USB DRIVE to laptop SSD?
 

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Thankyou very much. What role does the USB drive's READ speed play when copying files from USB DRIVE to laptop SSD?
It's the fastest you can write to the laptop SSD. USB will be slower especially with many small files, with larger files it's limited potentially by queue depth but with USB 3.1 Gen 1 would have a maximum around 460 MB/s under ideal conditions, assuming the laptop SSD can sustain that speed.
 
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It's the fastest you can write to the laptop SSD. USB will be slower especially with many small files, with larger files it's limited potentially by queue depth but with USB 3.1 Gen 1 would have a maximum around 460 MB/s under ideal conditions, assuming the laptop SSD can sustain that speed.
Hold on. Let me get this straight. So when copying files, it uses the SOURCE'S READ speed ?! o_Oo_Oo_O The Samsung BAR USB has 200 MB/s READ, using the port speed of 460 MB/s which you calculated earlier, that means when copying files FROM USB drive to laptop ssd, the WRITE speed of the SSD is 200 MB/s ???
 

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I have no knowledge on this. I trust you're 100% correct. Please correct me if I'm wrong, so when copying files from USB drive to laptop ssd, the MAXIMUM write speed of the SSD is determined by the PORT of the SOURCE, in this case a USB 3.1 Gen 1 drive ?!
Not just the port, but anything.

Speed is determined by the slowest device in the chain. No matter what it is.
You could have the fastest SSD, in a PCIe 4.0 port, in the most uber high speed PC, through the fastest USB port in existence...if the actual USB device is old and slow...that's what you get. Slow.
 

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Hi. I am curious, why does when copying from USB drive to laptop ssd, the source aka USB drive's READ speed is used?
The source can only serve up data at its rate.
The fact tat the target can accept data far faster does not matter.

Garden hose and fire hose.
If you have a garden hose (flash drive) feeding into a fire hose (SATA SSD), then only flow rate you'll get out of the end of the fire hose is whatever can come out of the garden hose.
 

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