We have a HP C7000 blade chassis with a HP Lefthand SAN solution. The ISCSI network is in its own VLAN and is using the standard MTU of 1500.
We also have a backup exec 2012 server that has read only access to the Datastores, and we use SAN based transport to backup the VM's directly off the lefthand. Everything works well.
Testing in my lab, I have found a large increase in backup performance when using jumbo frames. This is good news, I would like to configure the lefthands for 9000 MTU and configure the backup exec server for 9000 MTU also, but leave the ESXi hosts on the standard 1500 MTU.
All switches and network components in the paths have had jumbo frames enabled, just never used.
Thinking about it, I don't think this would be a problem mixing MTU's like this on a dedicated ISCSI network because the MSS is negotiated during the TCP 3 way handshake, and ISCSI works over TCP. There would be an issue if there was any UDP over that network, but I cannot think of any.
Can anyone offer any reason why I could not mix MTU's on a dedicated ISCSI network or any side effects that may result from it?