Jumbo Frames !!!!!!
-> Lets understand what’s Jumbo Frames first and how it benefits us …
- Jumbo frames are Ethernet frames with more than 1,500 bytes of payload (MTU). Conventionally, jumbo frames can carry up to 9,000 bytes of payload.
- Jumbo Frames allow ESX Server to send larger frames out onto the physical network. The network must support Jumbo Frames end‐to‐end for Jumbo Frames to be effective.
- iSCSI with jumbo frames gives better or rather much better performance .If you are getting sluggish performance then try enabling jumbo frames
So let’s activate it, I have used Jumbo frames only with SW initiator not HW one so if some can comment on how it works on HW it would be in for a great benefit.
Most probably you might have your VMkernel setup with 1500 MTU so we need to delete it and start over again. Its recommend to start from 0 but if you wish you can enable the jumbo frames on the fly, it won’t throw any errors.
In my case vSwitch1 was used as VMkernel for iscsi.
Step 1:
[root@esx sysconfig]# esxcfg-vswitch -d vSwitch1
Step 2:
Then I went ahead and did a listing
[root@esx sysconfig]# esxcfg-vswitch -l
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch0 32 3 32 9000 vmnic0
PortGroup Name VLAN ID Used Ports Uplinks
VM Network 0 0 vmnic0
Service Console 0 1 vmnic0
As it can be seen no VMkernel
Then lets start the stuff ………
Step 3:
Add a vSwitch
[root@esx sysconfig]# esxcfg-vswitch -a vSwitch1
Step 4:
List it….
[root@esx sysconfig]# esxcfg-vswitch -l
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch0 32 3 32 9000 vmnic0
PortGroup Name VLAN ID Used Ports Uplinks
VM Network 0 0 vmnic0
Service Console 0 1 vmnic0
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch1 64 1 64 1500
PortGroup Name VLAN ID Used Ports Uplinks
Step 5:
Lets set the jumbo frames AKA MTU
If you wish you can execute the below command on the fly to your vSwitch without deleting it
[root@esx sysconfig]# esxcfg-vswitch -m 9000 vSwitch1
List it to see the diference
[root@esx sysconfig]# esxcfg-vswitch -l
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch0 32 3 32 9000 vmnic0
PortGroup Name VLAN ID Used Ports Uplinks
VM Network 0 0 vmnic0
Service Console 0 1 vmnic0
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch1 64 1 64 9000
PortGroup Name VLAN ID Used Ports Uplinks
As it can be seen MTU is now 9000 not 1500
Step 6 :
Lets assign a NIC to the newly created vSwitch
[root@esx sysconfig]# esxcfg-vswitch -L vmnic1 vSwitch1
The result
[root@esx sysconfig]# esxcfg-vswitch –l
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch0 32 3 32 9000 vmnic0
PortGroup Name VLAN ID Used Ports Uplinks
VM Network 0 0 vmnic0
Service Console 0 1 vmnic0
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch1 64 2 64 9000 vmnic1
PortGroup Name VLAN ID Used Ports Uplinks
Step 7:
Lets give it a port group
[root@esx sysconfig]# esxcfg-vswitch -A VMkernel vSwitch1
Step 8:
Lets see Whether we got desired output
[root@esx sysconfig]# esxcfg-vswitch -l
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch0 32 3 32 9000 vmnic0
PortGroup Name VLAN ID Used Ports Uplinks
VM Network 0 0 vmnic0
Service Console 0 1 vmnic0
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch1 64 2 64 9000 vmnic1
PortGroup Name VLAN ID Used Ports Uplinks
VMkernel 0 0 vmnic1
Step 9:
Now lets give it IP
[root@esx sysconfig]# esxcfg-vmknic -a -i 192.168.0.11 -n 255.255.255.0 -m 9000 VMkernel
Hmm the output is ……..
[root@esx sysconfig]# esxcfg-vswitch -l
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch0 32 3 32 9000 vmnic0
PortGroup Name VLAN ID Used Ports Uplinks
VM Network 0 0 vmnic0
Service Console 0 1 vmnic0
Switch Name Num Ports Used Ports Configured Ports MTU Uplinks
vSwitch1 64 3 64 9000 vmnic1
PortGroup Name VLAN ID Used Ports Uplinks
VMkernel 0 1 vmnic1
Property of vmknic
[root@esx sysconfig]# esxcfg-vmknic -l
Interface Port Group/DVPort IP Family IP Address Netmask Broadcast MAC Address MTU TSO MSS Enabled Type
vmk0 VMkernel IPv4 192.168.0.11 255.255.255.0 192.168.0.255 00:XX:83:91:23:14 9000 65535 true STATIC
Source: http://moizzy.blogspot.com/2010/02/configure-jumbo-frames-in-esx-4-for.html