ESX 4 and iSCSI Offloading

[bookbinder]

I am trying to test out how to use iSCSI Offloading wiht ESX 4, I haven't been able to find much documentation and would like to test out the performance gains.

If it makes any difference I am using a Chelsio S310E-CR 10g adapter and I have been able to load up the driver in ESX, I just don't know what to do from that point to get the offloading setup.

Thanks for any suggestions!

[bookbinder]

Any word on how to setup iSCSI offloading with ANY vendor's card?

[CedricTechie]

Hi bookbinder,

As far as I known from ESX 3.5 and higher TSO is enabled by default , this implies you just need to configure ISCSI, vmkernel wil take care of offloading packet chunking business to the NIC, so no worries but please check the HCL if your specific NIC is supported, otherwise you should be good to go.

TSO is enabled by default on the VMkernel interface..here's how you check it, TSO MSS=40960 means TSO enabled

[]# esxcfg-vmknic -l

Interface Port Group IP Address Netmask Broadcast MAC Address MTU TSO MSS Enabled

vmk0 VMkernel 16.113.13.142 255.255.192.0 16.113.63.255 00:50:56:7f:ec:9c 1500 40960 true

[bookbinder]

What about the following:

When TSO MMS equal to 65535

[CedricTechie]

Hello Mate,

I see that you have checked it on vSphere, though the value is different, yes that number 65535 implies TSO s enabled, here's the supporting doc from VMware...

Snippet

Check Whether TSO is Enabled on a VMkernel Interface

You can check whether TSO is enabled on a particular VMkernel networking interface. Procedure

1	Log in to your ESX host's console.

2	Use the esxcfg-vmknic -l command to display a list of VMkernel interfaces.

The list shows each TSO-enabled VMkernel interface with TSO MSS set to 65535. What to do next If TSO is not enabled for a particular VMkernel interface, the only way to enable it is to delete the VMkernel interface and recreate the interface.

hope this helps..cheers

-Cedric

[amittul]

Hi Bookbinder,

Also refer to the KB articles http://kb.vmware.com/kb/1006143 which states about the Nic supported .

"Note: The Intel VT NICs (igb driver) and Broadcom BCM5708 and BCM5709 9 (bnx2) support TSO and LRO"

And also note - ESX does not support TCP Segmentation Offload (TSO) with IPv6

The below link which talks about the NIC’s which supports TCP/IP offload and accelerated iSCSI

http://h18004.www1.hp.com/products/servers/networking/index-nic.html

Thanks,

[amittul]

For Guest Windows machine you acan use netsh command to enable and disable to offload

netsh int tcp show global – Command to display the TCP parameters.

Ex:- Output of the above command.

TCP Global Parameters

-

---

Receive-Side Scaling State : enabled

Chimney Offload State : enabled

Receive Window Auto-Tuning Level : normal

Add-On Congestion Control Provider : none

ECN Capability : disabled

RFC 1323 Timestamps : disabled

For Windows Vista and Server 2008, use:

Enable: netsh int tcp set global chimney=enabled

Disable: netsh int tcp set global chimney=disabled

For Server 2003 and XP x64, use:

Enable: netsh int ip set chimney enabled

Disable: netsh int ip set chimney disabled

Thanks,

M@tr1x