New Duplicacy User questions About Threads


I have started using Duplicacy and i’m loving it so far great work!

I have searched the forum for these questions but i’m still somewhat confused.
I’m using the WebUI and i noticed its using 4 threads which was slow so i made it 6 and its way faster now.

  1. Will upping the threads cause any issues with my backups? is there any good advice when it comes to threads 4 was the default but it was slow for some reason?

  2. I’m using Backblaze B2 to back up and it asked if i wanted to encrypt (server side) my B2 bucket and i said yes, is this OK or can it cause problems with Duplicacy’s encryption?


B2 provides about 10mbps per stream. You are expected to use it multithreaded. 4 is a good default – but you can increase it if you want backup to occur faster, up to the limits of your upstream connection

Duplicacy already provides encryption. Encrypting again already encrypted data provides little value, only extra chores managing more keys.

Ok awesome i left it on 6,

Thank you for clarifying.

I have turned encryption off as Duplicacy does that already.

Thanks again.

It would be cool if there was a table with some guidance on this. Apart from internet speed, does the receiving device have a bearing? E.g. to HDD vs SSD, CPU, RAM etc.

I’m backing up from one home to another, on a consumer-grade connection to a fairly old computer with a 7200 HDD. I’m going to guess that 1 or 2 would suffice in those circumstances. But it is a guess.

There are too many factors; the easiest would be to keep increasing number of threads until no further improvements are observed, if speed is important. Or leave it at one thread: as long as all newly added data is backed up between runs there is no need to run it at full speed; on the contrary, it may be preferable for backup to go slowly to use as little resources as possible.

See the duplicacy benchmark command. You can test with multiple upload and download threads and find the optimal number of threads for uploading and downloading to/from your storage providers.