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Tcp offload iscsi and flex 10 with 10GB not working

Occasional Contributor

Tcp offload iscsi and flex 10 with 10GB not working

Hi we have two 7000 enclosures running with VC modules installed and connected to Cisco 4900M.
The blades bieng used are bl490c with the NC532i.The Machines are installed with Windows 2008 R2, the problem is we cannot get through put to iscsi disk subsystem to work consitantly over 100mb/s, if we enable tcp offload then we can amnage to get 300mb/s under a short period but then we get regular iscsi resets. We have aongoing case with HP but its going very slowly, and i have seen that there other having problems with the broadcom drivers and chips. So anyone out there
that can give me som hope that we can get better performance than 100mb/s. we are using iometer to measure the io.
Regards Craigg
Steven Clementi
Honored Contributor

Re: Tcp offload iscsi and flex 10 with 10GB not working


Can you give us any more details on your environment?

How many ports are connected to the Cisco Switch(es) from the VC Modules?

Are you splitting up your NIC ports? or using them as just a dual port card?

Is your iSCSI traffic isolated in it's own VLAN (or on the Cisco 4900M exclusively)?

Can you post some screen shots of your network and server profiles from the VC Manager?

Steven Clementi
HP Master ASE, Storage and Clustering
MCSE (NT 4.0, W2K, W2K3)
VCP (ESX2, Vi3, vSphere4, vSphere5)
NPP3 (Nutanix Platform Professional)
Occasional Contributor

Re: Tcp offload iscsi and flex 10 with 10GB not working

Hi there are one 10GB trunk into every VC module and the ports are split one of the ports goes to the ordinary network on a vlan and the other id dedicated for storage with its own vlan.

The iscsi offload is on its own vlan the storage vlan,and we are using the latest firmware and driver for NC532i. I looked at the revsion history for the driver and saw the follwoing information:-

Version: (9 Mar 2010)
Upgrade Requirement:
Recommended - HP recommends users update to this version at their earliest convenience.


This driver addresses an issue where where the ethernet connection is lost or ping stops for some time during high traffic conditions

It would seem to me that when we enable tcp offload we are getting 40/50% network throughput and this is causing the resets on the iscsi conneection. The driver versions after installation of the latest driver package are:

10GbE VBD driver version, NDIS 6.0 driver version, iSCSI offload driver version, diagnostic driver version and crash dump driver version

We have tested different scenarios on a test machine with the same outcome, there is however a difference if we enable tcpoffload from the command line using netsh and never user the gui, we getter better stability.