The best method is to setup like your first option.
A. create one vswitch including two vmkernels and attach two vmnics. Then each vmkernel bind one vmnic.
for each vmkernel portgroup, select one pnic as active and other pnic as un used.it is better to reduce the number of vswithces in the esx, but your second option also work, there is no fault in it. The multipathing plugin will do and control the failover of the iscsi paths.
now to your questions;
I have two questions about iscsi multipath settings.
Q1. When I create one vswitch including one vmkernel and attach two vmnics, not binding configuration, how does it work?
it will work as a normal networking, based on the teaming policy it will behave, if the teaming policy is "route based on originating virtual port id" in an instant the entire traffic will flow to one pnic only and the other pnic will be sitting idle so you will only get the network speed of one pnic. Because one vmkernel ip binds with one pnic and binds with one iscsi target IP.
If your teaming polic is '' ip hash'' there you will get some advantage, but you need to configure etherchannel in the pswitches, still you cant use the entire full bandwidth of the 2pnics.
So there is no advantage, but you have the redundancy.
That is why, as per the best practice, create a single vswitch and create each vmkernel port group for each pnic, and then in the port group teaming policy setting on FAILOVER ORDER select '' over ride switch failover order' then make on pnic as active and all other pnics as unsed. do the same for all the vmkernel portgroups.
So each vmkernel portgroups will have one IP and it will establish a one to one connection with the iscsi target IP. thus you will get optimum performance.
Q2. When I have two VLANs for iscsi, dose the following configuration work?
- create one vswitch including fore vmkernels and attache two vmnics. then each vmkernel bind one vmnic.
this will make the entire system more complex, simply you configure one vlan in the storage, and use that in the vmkernel also, then configure those vlan in the pswitch. Why you need 4 vmkernel portgroups ? you only have only 2 pnics right?
Again, the entire thing depend on the ISCSI storage array, how many targets are there in the storage that is how many pnics are there in the storage?
and is it active/active or active/passive ? and also there should be atleast 2 pswitches one for each pnics and jumbo frames must be enabled.
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(vExpert, VCP-Cloud. VCAP5-DCD, VCP4, VCP5, MCSE, MCITP)