VMware Solutions Discussions

Set MTU On Active Ethernet Device


Is it possible to change the MTU from 1500 to 9000 on a single VIF that is currently in production without any NFS client connected to it experiencing downtime?

We have a FAS3240 Running DOT 8.0.2P3 and the VIF in question is a single 10GbE link with no trunking or routing, but we do have several active NFS connections utilizing this VIF (VMware datastores) that I'd like to keep active during the MTU change.  The plan is to:

1. Setup MTU On Networking equipment (DONE)
2. Change MTU from 1500 to 9000 on FAS3240 for NFS VIF (ifconfig nfs mtu 9000, as well as update /etc/rc)

3. Change MTU from 1500 to 9000 on ESXi 5.1 Hosts (that are in maintenance mode)

I'd like to do all this without shutting down or shuffling the VM's that utilize the NFS VIF.  Is that risking data corruption / filer or ESXi 5.1 host crashing?




I believe you can do an ifconfig command with the new MTU size on the filer. You can verify it with ifconfig -a.

I suggest making sure the network MTU size is greater than 9000 first.

I would also make sure you can do this on both ends quickly, it can cause high processor utilization on some network equipment to support both MTU sizes.