RHEV 3 Beta Setting MTU on Storage Interface

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What is the current best practice on setting MTU of the interface that accesses iSCSI storage network?


Thanks in advance,



This isn't available in the GUI (but will be in 3.1)

You can manually set the mtu on the ifcfg-ethX device MTU=9000



If the device is actually a logical network (ethX+bridge with bonds and vlans in the middle sometimes), make sure all the devices that build up the logical network have the MTU=9000 param set up.

The interface is dedicated ethX for the storage network only. Was just wondering where to set it up properly as I heard rumors that if you modify those ifcfg-ethX-files manually they would be over written on hypervisor reboot.

If the ethX you are using has no logical network attached, you should not worry. Just make sure the ifcfg script is persisted, if you're using RHEV-Hypervisor

How do you "persist" it on RHEV-H hypervisor?

You will need to the root console for that, but since you're making manual changes anyhow, I suppose you're already there.


to make a config file persistent, just type 

persist /etc/sysconfig/network-scripts/ifcfg-ethX



Note that persisting works only for small config files in specific locations, you cannot just persist anything anywhere in the RHEV-H system

The network config files are automatically persited.

Once a file is marked as persisted (adn the network files already are) then you can change it without running persist.

Ok thanks Dan and Andrew for the quick replies. We will try that "persist" route. For some reason on our RHEV-H installs the root-account is not disabled so you can log in as root without logging as first admin, then from menu choosing F2.