kopia: High Memory Usage

Hello. I’ve been a user of borg + rclone for years and have recently found Kopia. It looks like a really great solution to backups I’d like to switch to.

I first attempted to use kopia-ui on Debian. My repository type is Filesystem. I attempted to simply backup my $HOME which is ~400GB. During this backup within a few minutes kopia proceded to use my entire systems memory spilling over into the swap.

Looking at the logs the only thing weird that I noticed was a line that said(Not sure if it matters):

/home/user is not under /home/user

After the memory issues I had above I attempted to do the same thing via the command line. I set parallel=4 to attempt to slow down the data coming into memory and it seemed to help, but the problem still ended up happening before the end of the backup.

After doing a little more investigation I noticed that the amount of memory I’m using is the difference between the hashed files, and the uploaded files. I’m taking a guess that because I’m saving my snapshot to a slower I/O device than the source that kopia is simply getting behind and doesn’t throttle/back-pressure at all?

Any help would be greatly appreciated.

EDIT: Setting parallel=2 allows the backup to finish, but still uses a large amount of my RAM. I guess this is intended behavior? Setting parallel to the right number for your I/O is necessary?

EDIT 2: After using kopia the memory that’s used never gets freed. I have to restart even after killall the kopia processes. Anyone have any ideas?