Starting VM changes bridge MTU of vmbr0

adoII

Renowned Member
Jan 28, 2010
182
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Hi,

i am using Ceph Storage with a MTU of 9000 and VLANs and bonds
So my eth cards have MTU 9000 and the bonds also have MTU 9000
on the different vlans i have different mtu ranging from 1500 to 9000

My vmbr0 has a fixed mtu of 1500 defined in /etc/network/interfaces

Now, when I stop and start a vm the mtu of my vmbr0 is changed automagically to 9000 by proxmox.
I can change MTU on shell back to 1500 but i can always reproduce that starting a vm changes the mtu back to 9000.

I want vmbr0 mtu to be 1500

Problem is now: I have different servers and when some are sending with mtu 9000 and others are sending with 1500 my corosync communication will sometimes fail.

Is there a way to prevet proxmox from changing system MTU ?