iSCSI, networking design questions

[baubau01]

Hi guys,

We have 2 SANs one is EQ and one is RS16. We have 10 hosts with 4 dedicated nics for ISCSI traffic and 2 ISCSI dedicated 5448 Dell switches.

The way we had it setup was to have 4 Vswitches with 1 physical nic each and  2 virtual ports each (one from EQ and one from RS16)  jumbo frames enabled etc.

Now Dell kinda wants one of the 2 things for better performance:

1. Have 2 physical nics only for Dell and have 2 physical nics only for RS16 san. This will reduce our 4 paths to each san to 2. How is this improving peformance really ?

2. They want to use one Vswhitch with 2physical nics and 2 vmkernal ports.

I read VMware ISCSI guide and they say you can do it both ways. I beleive the 1vswitch to one physical nic is best way and we `ll end up with 4 vSwitches. Each of our Vswitch will have 2 vmkernal port one for EQ and one for RS16.

Please let me know your thoughts for best performance ?

Thanks

[vmroyale]

Hello.

Note: This discussion was moved from VMware vCenter Server community to the VMware vSphere Storage community.

I also like the idea of having the traffic split out across the storage arrays.  Are you using, or planning on using, the EQ MEM plug-in?  That would improve performance for the Dell, and leave you with one vSwitch with two pNICS and 2 VMkernel port groups.

Good Luck!

[baubau01]

I just tried to use MEM and as soon as MEM is the policy from 4 connections to the SAN drops to 2 and performance is awfull. So I switch back to Vmware RR it sees them all 4 and performance is ok.

Why would you separate the 2 SAN traffic ? Wouldn`t you want both sans to have 4 shared between the 2 rather than 2 each ?

[baubau01]

no`one else ?

[RobVM]

We use the Dell recommended setup with our EQ SAN. Two pNICs, two VMkernel port groups, one vSwitch, the EQ MEM plug-in. Performance is good. Each host has 6 connections to each volume, three from each NIC. You might try configuring one host that way and testing it to see how it works in your environment, use tools like IOmeter and EQ SANHQ to see what your performance and latency is like with each setup. We do not have a dual SAN configuration so I can't offer any specific advice whether to segregate or not.

[ShannonZ]

From my point of view and experience, it's better to keep one SAN but two Fabric to ensure network redundancy. Thus it can keep 4 paths in your setup but just make sure to connect different set of 2 paths to the 2 arrays' primary controller port (If the array is A/P array). In order to make sure this config, you need using storage multipathing (create one vmknic for each pnic and do port binding) instead of NIC teaming, and using VLAN to isolate each storage I/O path.

And I think it doesn't matter to have one vSwitch or 4 vSwitches, you just need to create 4 vmknics to do port binding with each pnic and get 4 iscsi storage I/O paths.

Thanks,

Shannon