How to see transfer rate of file copies?

If you can use the terminal then you can run

iostat -dw2

to show io rates every 2 secs (across all apps but if only 1 app, eg Finder is doing much...)

Other flags are available to change what you get, see man iostat

footofwrath wrote:

II currently use Double Commander because it gives me this information. Is there a way to see it in Finder as well?

No. There's just the progress bar.

footofwrath wrote:

No kidding but if I see the rate is very low I might look into a bug or something.

If you feel a transfer is too slow run BlackMagic Disk Speed Test app and see what it indicates as the read and write speed is. You can select the file it uses for the stress test up to 5GB.

I sometimes try to check it via Activity Monitor > Disk > DATA read/written.

As no one here works for Apple, if you want a future implementation of Finder to display copy transfer metrics, you will need to request a feature enhancement with the macOS product team. Apple product teams do not participate here and likely have any free time to review posts here if they are allowed to do so. Since not everyone wants to see these metrics, it probably should be a toggle setting in Finder Settings.

Direct feedback to the macOS Product team.

No. Apparently not a design criterion. Seeing the speed won't improve transfer time.

Writing a large file (gigabytes) has to take less “time-out” to modify metadata, then if you are writing lots of small files.

Writing the data for a large file just needs to allocate storage every so often. Allocating storage involves updating metadata that keeps track of free storage, updating metadata in the file that tracks the storage it is holding, and writing the data. If the filesystem guesses you are writing a huge file, it may allocate huge chunks of storage each time the file needs more storage, so the allocation side issues will happen less. And when finished, the file’s timestamps must be updated.

Writing lots of small files involves all the storage allocation issues, plus, the file system needs to first allocate the files metadata that holds the files storage, holds the file ownership, the file dates, the type of file (file, directory, symlink, FIFO, device, Socket, …), and other misc file data. Then the file name needs to be added to the directory where the file can be found, which may require the directory to grow and allocate its own additional storage. Copying small files is a lot more work, than copying huge files.

I’m glossing over lots of other stuff.

My day job is working on a commercial Unix/Linux filesystem.

Feel free to send Apple feedback about your concern if you like.

Feedback - macOS - Apple

footofwrath wrote:

I don't get your angle man. If it's not possible that's fine - you said that already. No need to imply that I shouldn't want something just because you don't think you need it.

I don't understand your comment. I didn't state or imply you shouldn't want something.

The relation between raw speeds reported by BM DST and actual file copying between disks can be huge. I see 350MB/s BM test but more like 40MB/s average copy across a group of diverse files... (though iostat shows the rate varies second by second 10MB to 130MB). This is on M1 mini that is hugely unloaded doing nothing of note at 5% cpu.

I'd love to have time to explore why that happens! Is it throttling? Using raw cp in terminal is even slower BTW.

How large are the files you're trying to copy to the EHD? How much free space do you have on your EHD? It could be that the Finder is taking time to find bit and pieced of free space to store the image file(s).

If it's several very large files you might try using  to "clone" them to a folder on the EHD. Might be quicker. There's a demo version you can try to test.

It sounds like you already have an app that does what you want.