iSCSI Port-Binding and Multipath

[Robin23]

Hi

i have one question about port-binding and multipath, i am searching internet for hours without finding the answer for my question

I know how port-binding works (iscsi targets and initiators must be in the same subnet/broadcast domain) but how to configure multipath if this is not the case?

in my example, setup looks like following

iSCSI-01 has 10.85.20.10/26

iSCSI-02 has 10.85.20.70/26

Storage-Controller 1 has 10.85.20.20/26

Storage-Controller 2 has 10.85.20.80/26

means iSCSI-01 is in same subnet with Storage-Controller 1 and iSCSI-021 is in same subnet with Storage-Controller 2.

So according to vmware documentation (eg VMware vSphere ISCSI Port Bindings – You’re Probably Doing it Wrong | virtual.mvp) i am not supposed to use "VMkernel Port Binding" (as it is configured right now):

but if i remove "iSCSI-02" from the iSCSI Initiator, there is no more multipathing as only one vnic is used for iSCSI. Is there a possibility to use multpathing without port-binding? How can i have redundancy without port-binding?

Thanks for your help!

[hussainbte]

Not possible to have multipathing with iSCSI port-binding.

you wll not get redundancy from the ESXi host side if the vmkernel is not linked to the iSCSI initiator.

Check the below link also. same stuff.

http://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/vmware-multipathing-configuration-software-is…

[Robin23]

sorry, i dont get it. I guess you meant "Not possible to have multipathing WITHOUT iSCSI port-binding", right?

yes, that is exactly my question, so there is no possibility to have multiple vmnics in different subnets along with iSCSI controllers (as described in my initial post) and have redundancy? Is there really no other way?

thanks

[RAJ_RAJ]

Hi ,

In vSphere environment Without port binding there you won't get multipathing or load balancing  .

Also one more thing if you have teaming configured , connectivity will be there through other NIC if first NIC failed but failover at the path level will not be there .

[Robin23]

thanks for the answer even if it is really disappointing. So no iSCSI loadbalancing/multipathig if routing is needed or devices are not in the same subnet.

Then iSCSI best (and only practise) is to place all adapters in the same subnet as otherwise only one vmnic can be used.

Is there a way to add another "iSCSI Software adapter"?

Thanks

[RAJ_RAJ]

Hi ,

You need multiple vmk for multipathing , if it is in same network also it will work .

As of now only one software iSCSI adapter available  . If your hardware (NIC) supports you may use hardware iscsi configuration 

[Mattallford]

What happens if you remove both vmkernel adapters from the port binding?

What sort of array are you connecting to?

What discovery addresses are configured on the software initiator?

[RAJ_RAJ]

if you remove both vmk  , associated data store will become unavailable , check below image .

Array will be block type H/W (iSCSI)   or any software which supports iSCSI storage like openfiler , starwind etc 

discovery will be based on Initiator - IQN and iSCSI target Address (Server IP )

[Mattallford]

As already discussed, using port binding when the vmk interfaces are on different subnets  is not recommended. That's why I'm asking the OP if they have tried connectivity to the storage without any port binding configured on the iSCSI software initiator. I've only been involved in single subnet configurations, but I would have thought that multipathing would work when using different subnets / VLANs for iSCSI traffic. Each VMK would establish a path to the relevant storage IP endpoint (on the same subnet as the VMK), and the PSP would determine the traffic paths.

I'm also asking specifically what type of storage it is, as the vendor will likely have some guidance and recommendations in connecting to their arrays over iSCSI.

[RAJ_RAJ]

Hi ,

Normally iSCSI traffic will be isolated so everyone prefer to use single network .

But if you want to configure that , you can configure that and data store will be visible if one link down also but not sure mutipath will work properly or not . About  type of storage   - You may go with EMC or  Dell

[Garry_N]

You mentioned StarWind, why don't you try setting this up like they do?

You can configure 2 separate vSwitches and assign 1 NIC + VMKernel per vSwitch. Then you should be able discover iSCSI via dynamic/static and have 2 paths that can be set to either RR or Load Balancing.

Also, I saw StarWind will soon release new gui-less free version that will allow HyperConverged scenario in production :smileyhappy: