Ubuntu sync struggling

I am new to NextCloud and I set up a NextCloudPi server on an RPI4 with a 1TB SSD on a USB3 port and a Gigabit Ethernet connection. I synchronised 162 GB of files to it from a Win7 machine and was impressed by the speed they uploaded and everything looks good in the web view.

I then set up a sync client on a Ubuntu machine that is about twice as powerful as the Win7 machine, 8 cores, 32 GB RAM, 1TB SSD on an m.2 card also on on 1GB Ethernet. It has taken it a few days to sync and has showed lots of errors about getting zero length files, etc. Even though it says it has synchronised the activity shows it is still syncing files. It also spends long periods being unresponsive.

Am I expecting too much to be able to handle this amount of data with NextCloud?

When it shows errors that go away will it correct them? Is that what the current activity is?

Is there a chance it will corrupt the files on the server by syncing the truncated versions back to it?

I had been warned that NextCloud was flaky, is that the case on Ubuntu?

I’d check the usage on the raspberry pi during the downloads. The client does per default parallel downloads, perhaps it creates too much load on the raspberry pi so it fails. In this case you could reduce the number of parallel downloads. I’d try slowly with only a partial sync, so start just with one folder and check the performance.

I don’t know to which extent the NextcloudPi image was optimized for the new RPi 4, if it wasn’t there is probably some potential to boost the performance. For a Raspberry 2/3, I’d say you have to go slowly, 100 GB are not a problem but if several clients to things in parallel, you can expect wonders from these small computers. The 4th version should be better, unfortunately, I don’t have any benchmarks.

You can do a full/partial second sync on Windows by setting up another folder and syncing the same data from the server. This will tell you whether the issue is the download process or something specific to Ubuntu or its client.

I would not be too quick to call the server software flaky when running it on a low spec system and using USB for storage. Raspberry Pi is great, but it sounds like you’re putting some load on it too.

Yes I have synced a Win7 laptop to a subset of the data and that worked fine. I don’t have enough disk space for all of it.

I just seems to be the much more powerful Ubuntu machine that struggles. The sync app is periodically unresponsive and it did show a lot of errors initially but seems to have settled down now. However, despite all the folders showing green ticks and that they are synchronised, the activity log keeps saying it has synchronised files that haven’t changed in years.

The activity logs of my two Windows machines match and end with the files I have edited recently.