Comments 8 Posted In Red Hat Virtualization RHEV 3 Beta Setting MTU on Storage Interface Latest response 2011-12-07T14:21:21+00:00 Hi, What is the current best practice on setting MTU of the interface that accesses iSCSI storage network? Thanks in advance, Toni TM Started 2011-12-07T12:50:34+00:00 by Toni Mattila Active Contributor 155 points Log in to join the conversation Responses Sort By Oldest Sort By Newest AC Red Hat Active Contributor 245 points 7 December 2011 12:59 PM Andrew Cathrow 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 DY Guru 5340 points 7 December 2011 2:01 PM Dan Yasny 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. TM Active Contributor 155 points 7 December 2011 2:04 PM Toni Mattila 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. DY Guru 5340 points 7 December 2011 2:08 PM Dan Yasny 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 TM Active Contributor 155 points 7 December 2011 2:10 PM Toni Mattila How do you "persist" it on RHEV-H hypervisor? DY Guru 5340 points 7 December 2011 2:17 PM Dan Yasny 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 AC Red Hat Active Contributor 245 points 7 December 2011 2:19 PM Andrew Cathrow 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. TM Active Contributor 155 points 7 December 2011 2:21 PM Toni Mattila 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.