Copy Speed Test Results to USB 3.0 Drive w/ SSD - why so slow?

The slow CPU and limited memory in the RN102 likely is also a factor.

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chadwixk wrote:

 

SOURCE: 

The NAS disks are WD Red 5,400rpm, capable of around 110 MB/s reads each. This is a RAID 1 of 2 disks, so assuming it could read in parallel from each disk to have a potential of double that right?

 

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Theoretically, yes.  But from what I've read (posts on other forums), a single file is only read from one disk.  A second file copy should be read from the second disk if it is done at the same time.  But this is not something I've tested.

chadwixk wrote:

 

But Why, since it is a direct link over USB and sourced from 2 disks in RAID 1, was the speed not near the theorhetical 220 MB/s (read from 2 disks in parallel at 110 MB/s each)? I tried copying multiple files to try to take advantage of this, but I guess these copy commands are sequential in nature...I'll have to look to see how you could actually copy 2 files in parallel to test this aspect further.

 

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Use two ssh sessions to test this.

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chadwixk wrote:

 

DESTINATION:

A usb NVME drive to the rear USB 3.0 port. It is a Samsung 970 Evo SSD with write speeds of around 2,500 MB/s .

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But USB 3.0 is ~600 MB/s, so it would be the write bottleneck.  Or possibly the NVME adapter you used???

Did you measure the read and write speeds on the RN102 using dd?  Might be worth doing (for both source and destination).

FWIW, the NVME formatting might also be relevant here.  NTFS is likely slower than ext.

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chadwixk wrote:

 

Windows drag and drop...isn't this a copy over the network, to the client and then back? NAS > Windows Client > NAS > USB Port > NVME SSD? 

 

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Yes.  As is robocopy.

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chadwixk wrote:

rsync -hvrPt --info=progress2 --ignore-existing "/data/Videos/2022/12/2022-12-20-063917.mkv" "/media/USB_HDD_7/Videos/2022/12/"

 

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No one ever accused rsync of being fast.  It also verifies, which will of course make quite a difference in transfer times.  But might be worth the performance penalty.

If you add --checksum-choice="None", it should be somewhat faster.

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chadwixk wrote:

 

TEST RESULTS:

ssh > cp: 18 MB/s

cp -r -u -v "/data/Videos/2022/12/2022-12-20-063917.mkv" "/media/USB_HDD_7/Videos/2022/12/"

 

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This one is surprising.  It might be worth copying to /dev/null to test the read speed (in addition using dd to test read and write speeds of both devices).