Rclone crashes macOS on local transfers

Thanks @Ole for your help.

Yes, after some performance tests, it seems that the limiting factor is in the SFTP server. Specifically, in its hard disk. While the Mac can read at about 1200 MB/s, the SFTP server can only read at 350 MB/s.

In terms of MD5 "read + compute", the Mac slightly drops its performance to 1060 MB/s and the SFTP server to 295 MB/s.

With this, I think we can conclude that, in the picture shared before (with transfers completed over several minutes and CPU usage on the Mac dropping to 1%):

Looks like that's not a rclone freeze, but is the Mac waiting for the SFTP server to finish the md5 calculations before it can continue. I have monitored the server with "top" in those instants, and that's what seems to be happening. Do you agree?

On another note, and back on topic, yesterday, after a long time without happening, I have again experienced a "Finder" freeze during a rclone transfer. At first glance, it's just the Finder freezing, but it's hard to tell what's really happening on the Mac. Although, it is definitely not a system freeze, nor a crash, as it is possible to restart the computer normally.

This is more like, but not the same as, what @wdp experienced.

This is the log during the Finder freeze (macOS 13.2 Ventura).

Wow, this became far more active than I expected. Thank you all.

As much fun as it was crashing my laptop on purpose, I had to get some work done and haven't had a chance to get back to replicating the issue yet. I am really impressed with the rclone community though. This is amazing to see. Normally people just say I'm using the tool wrong and to read the manual. I was a few days in on troubleshooting before I even made it to the forum.

Hopefully I will have some time this weekend to go back through the suggestions and get more specific information to you. I do know I can replicate it frequently though. Sometimes, very rarely, the transfer makes it.

Yes I do, great testing!

I suggested trying the hasher in this post, I guess it can take much of the load from the SFTP server - especially while checking.

An ordinary rclone sync like yours should not be able to make the Finder freeze unless there was a major memory leak in rclone, but we already know the rclone memory usage is within expectations and low.

My immediate thought is therefore that the sync is pushing some (unstable) part of the Mac OS over the edge. It could be anything, but my immediate suspicion in your setup would be the something related to networking, e.g. your network driver or high packet loss on your network. This is because you already tested that high concurrent CPU and disk usage didn't trigger any issues while trying rclone check.

I therefore suggest you start ping IP.OF.YOUR.NAS in a sperate terminal during your sync and then monitor it up to and during a freeze.

Does your Finder show networked drives e.g. from the NAS?

Good to hear from you.

I also suspect your issue is related to the SMB driver, network driver or network being pushed hard by rclone.

Here is a little test what will probably run without issues:

rclone check ~/Desktop/temp_photo/ ~/Desktop/temp_photo/

and here is another that may provoke the issue:

rclone check /Volumes/Illmatic/ /Volumes/Illmatic/

Like rapid arm movements/seeks? Could there be a bad spot on your disk?

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