RHEV 3 Beta Setting MTU on Storage Interface

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Hi,

 

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

 

Thanks in advance,

Toni

TM
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Responses

AC Red Hat Active Contributor 245 points
7 December 2011 12:59 PM

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

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

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

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

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

DY Guru 5340 points
7 December 2011 2:17 PM

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

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

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.