slow proxmox backup

[nitaish]

We have a Proxmox node with 32 GB RAM and a Xeon Quad Core processor w/HT. We have created a single Windows 2012 R2 VM with 30 GB RAM and 8 cores assigned. The storage is SATA and so is the backup drive. There is no issue with the performance of the VM except when the backup is taken using vzdump. I checked the write speed of both the storage drive and the backup drive and got more than 400 MB/s speed on storage drive and over 300 MB/s on the backup drive. The speed does not seem to the issue. However, the backup takes a long time and the VM slows down during the backup. It takes more than 24 hours for a complete backup. The actual usage on the storage drive is 726 GB. I have a similar server with a larger storage and there is no issue during the backup. What could be wrong?

 

[sahostking]

I am noticing something similar not too sure yet what is the cause but servers run perfectly fine during the day its when we run backups then for some reason its slowing down VM considerably. Its like moving from SATA to SSD makes no difference. I am starting to think it may not be vzdump as we did limit the transfer speed and then also not limit it with no real difference. But when we turn off lzop compression it seems to run much much better.