SSD

[danyg]

I've got a Scan Disk Extreme Pro SSD 4TB USB-C for my M1 Macbook Pro.

Copying files from my computer to the disk is pretty fast. 7GB something like a few seconds
Copying files to my computer from the disk is very slow. (like 10 times slower)

What could be the reason?

[JFreak]

Please download the Blackmagic Disk Speed Test app and post results.

[danyg]

thank you

Target Drive Mac SSD User Folder: ... around 5500 MB/s for write and read.
Traget Drive Scandisk SSD: .... around 900 MB/s for both

[Darryl Ramm]

Speed test is a good idea.

What filesystem is on the external drive?

How exactly is the drive connected?

How exactly are you copying over stuff?

Where exactly are you copying files to on the Mac internal SSD? Especially be aware of cloud storage folders, including iCloud shared home directories (that you should not have enabled).

[Darryl Ramm]

Originally Posted by danyg

thank you

Target Drive Mac SSD User Folder: ... around 5500 MB/s for write and read.
Traget Drive Scandisk SSD: .... around 900 MB/s for both

Basically what you expect. And with SanDisk confusing product naming it’s unclear exactly what model/generation drive you have… but even if you had a USB 3.2 2x2 (20Gbps) drive you only get support for up to USB 3.2 Gen 2 (10 Gbps) on Macs… Apple trying to “protect” Thunderbolt???

[danyg]

I'm not a tech guy. So the numbers are correct?

The drives says: ScanDisk Extreme Pro Portable SSD, Model sdssdE81-4t00

Format Mac OS Extended (Journaled)
Singel USB-C cable
f.Ex Files from Mac Download folder (Wetransfer) to disk or back

[Darryl Ramm]

Originally Posted by danyg

I'm not a tech guy. So the numbers are correct?

The drives says: ScanDisk Extreme Pro Portable SSD, Model sdssdE81-4t00

So as I guessed before you have a USB 3.2 2x2 drive, here running at half speed (USB 3.2 Gen 2 aka 10Gbps) because it’s connected to a Mac, and you see what is expected in the Blackmagic speed test.

Format Mac OS Extended (Journaled)

Unless you have old Mac computers you need to use this external drive on you should be using the more modern/robust/efficient/flexible(with containers) APFS filesystem. But this is not likely to explain whatever you are seeing. You might as well reformat that external drive as APFS if it does not have a lot of data on it yet (copy and move back any data that is there before/after you format the drive).

f.Ex Files from Mac Download folder (Wetransfer) to disk or back

Yes but how are you doing this? Dragging and dropping a folder? From the command line? How large are the files, etc. Are you sure you are copying the same stuff each way? What does the command line du -s command show for all the files copied to/from these drives (put them all in one folder and copy that each way, renaming it on the target drive in the copy command and then run du-s on the source and target. There can be pathological cases of large files that appear to be large but are smaller than they appear, or expand to much larger when copied to an external drive so even if they might for example copy much faster within the same APFS drive than they do going to an external drive, even allowing for drive speed, etc. newly created large zip files are good ones to try dragging and dropping between drives.