iSER support on Starwind VSAN appliance for Vsphere

[pso3g]

Hello,

I'm trying to configure HA on a 3 node vSphere 7 cluster (Essentials Plus) using StarWind VSAN Free. Networking is based on Mellanox ConnectX3-Pro (for sync) and ConnectX4 (for iSCSI/heartbeat), which are passed-through to the corresponding VSAN nodes. I'm following most of the tips I've read on your documentation to maximize performance as much as possible. However, when using the Linux appliance I can't enable iSER functionality. The option is greyed out on the Management Console and shown as N/A for both cards. I've set up a Win10 testing VM with Starwind VSAN software and, after installing the Nvidia/Mellanox OFED drivers, iSER can be enabled without problems, so the cards are compatible.

Could you help me with this issue or is iSER not supported on the VSAN Linux appliance? Ideally, I would like to avoid the need of windows server VMs as much as possible.

Thanks in advance!!

[yaroslav (staff)]

Greetings,

Thank you for your question. If your production mostly consists of VMs, iSER will not grant sufficient performance https://www.starwindsoftware.com/blog/s ... technology. Furthermore, it improves CPU utilization inside the Linux VM. CPU utilization inside of the VM, based on my experience, is rarely a bottleneck.
What I am trying to say is that I believe that you are fine to go with traditional iSCSI to present the storage over the network.

[pso3g]

Thanks for the answer. In the meanwhile I configured a windows server based cluster so I will be able to enable iSer, at least for the sync link. Without considering the license cost, would you recommend using a Windows Server based deployment over the Linux/Wine approach?

One more question which I have not yet been able to fully solve for an hyperconverged scenario: as every ESXi server will have a running Starwind VSAN node, how is that locality exploited? By looking at the documentation it seems it just configure the iSCSI VSAN on the ESXi servers just as if it were an external system with a link to every node using a round robin access. I mean, I'm fairly new to the VSAN approach, but I guess it does not really make sense to use the real network over the virtualized "in-memory" one as long as the local VSAN node is up and running right?

Thanks in advance!!

[yaroslav (staff)]

For nested scenarios (i.e., deploying StarWind VSAN inside a VM on top of ESXi), StarWind-VSAN for vSphere works better.
StarWind VSAN provides active-active HA storage, replicated between VMs on top of ESXi servers. Each VM presents HA device(s) to its host and to its partner. True, the storage is "external" as it is presented over the iSCSI network.
You could connect the Internal adapter with VMK.

[pso3g]

Ok, long story short, forget about iSER on a vSphere based scenario, I got it . I had almost decided to go the Windows way to be able to enable iSER on the sync network, hence offloading CPU workload as much as possible. However, if you tell me overall performance for running VMs is better with the CentOS/WINE appliance approach and no iSER I will stick to it.

Regarding the iSCSI network connection, is there any way to "force" each ESXi to use the local node over the others when available? if so, does this improve performance vs a round-robin access?

[yaroslav (staff)]

There are many virtualization layers in the nested scenario which slow the performance.
Furthermore, VMware iSCSI Initiator itself is likely to be a bottleneck.