So, I've been running offsite copies to OVH S3 bucket via PBS running as an VM but I ran into an issue that verification of the backups is so slow that they're practically unusable.

Copies run nightly and I've set the storage to keep last 4 copies in place. Bigger VMs, like my immich-instance with a bit over terabyte of data, take several days to verify and logs show data rates at around 5MB/s or less. So, with the current schedule I'm running it'll mean in practise that backups expire before they're verified.

I could keep the copies longer, but that'd cost more, or run copies less frequently, which risks losing data if hardware fails at unfortunate moment (which it most likely will). Tuning settings are on default and based on what I've read, adding more runners wouldn't really help that much.

PBS VM itself shows very little load on proxmox monitoring and I've got plenty of bandwidth to use, so the verification shouldn't have any bottlenecks on my end at those speeds. Cache usage is at around 60% with ~30GB of total space available.

Does anyone have any ideas on how to speed that up? Or should I just give up and do something totally different? I attempted to run backups to Hetzner storagebox over cifs-mount, but that's pretty much the same or worse with performance.