When having 2 networks which one will be used as backup by default. How to change it?

[nwongrat]

I have 1Gbps network and 10Gbps network. Right now the management network is on 1Gbps. All the VMs running on 10Gbps network. I thought that when doing backup system will used the VMs's network. TodayI try disable all VMs network but all the VMs can still do the backup. I guess, they must be using management network to backup.
Can I change the backup network? For example, Backup use 10Gbps and Restore use 1Gbps?
In other words, Can i specific what activity ( not just the backup ) use specific network?

 

[narrateourale]

but all the VMs can still do the backup.

Do you do backups with Proxmox VE itself, or with some other backup solution within the VMs?

Overall, which network is used, from a Proxmox VE view, depends on the IP addresses configured. If you want to separate it, for example, have backups on the 10Gbit network, then you need to use different subnets for each physical network. For example: 192.168.1.0/24 for the mgmt and 192.168.10.0/24 for the other network. Then you use the respective IP address in the storage configuration.
This is necessary, because if you configure two different IP addresses in the same subnet on two interfaces, the Linux kernel might answer on the other interface as it handles same subnets on different NICs in an opportunistic way.

Can I change the backup network? For example, Backup use 10Gbps and Restore use 1Gbps?
In other words, Can i specific what activity ( not just the backup ) use specific network?

No. But if you restore, you can define a rate limit for that restore operation if you don't want to use too much bandwidth. Or you define a global "backup / restore" limit in Datacenter -> Option -> Bandwidth limits. But the global one will be for both, backup and restore.