slow pbs when backed-up vm is on cifs share

[RolandK]

i have some powered-off VMs which are located on a cifs share. i use those for "parking" unused VMs.

i have observed, when these VMs are getting backed up with pbs, performance is terribly slow. (<< 500Kb/s).

migrating the virtual disks from/to the cifs share is fast (100Mb/s).

what is the reason for the slow pbs backup speed?

 

[RolandK]

this could have been the reason:

https://forum.proxmox.com/threads/weird-samba-performance-bug-issue.154258/