vSphere 6.7 iSER setup with Mellanox ConnectX-3

Thu, May 21, 2020 2-minute read

I wanted to see if enabling iSER for my ESXi servers would improve the performance of iSCSI, since RDMA should offload a lot of cpu cycles.

Unfortunately it is not just a matter of checking a checkbox in ESXi to get it enabled and working, and even if you do all the required steps - it might just not work anyway.

For my Melanox ConnectX-3 (non pro) I had to this on my ESXiinstallation(s)

#enable iser module
esxcli system module set --enabled=true --module=iser
#adds the rdma iser adapter - without this you will not have an iser adapter to configure
esxcli rdma iser add
esxcli system module parameters set -m nmlx4_en -p "pfctx=0x08 pfcrx=0x08"
esxcli system module parameters set -m nmlx4_core -p "enable_qos=1 enable_rocev2=0"
esxcli system module parameters set -m nmlx4_rdma -p "pcp_force=3 dscp_force=24 dscp_to_pcp=0"
#tag the vmkernel adapter with VSAN, exchange vmk0 for whatever interface(s) you use for iscsi
esxcli network ip interface tag add -i vmk0 -t VSAN

That should be the setup on the ESXiside - furthermore i had to ensure the the Mellanox cards were set up correctly for iSER - according to Mellanox iSER is not supported if you have SRIOV enabled, so to disable that on the cards itself I had to first install Mellanox’s management software on my ESXi’s.

cd /tmp
wget https://www.mellanox.com/downloads/MFT/vmware_6.5_native/nmst-
wget https://www.mellanox.com/downloads/MFT/vmware_6.5_native/mft-
esxcli software vib install -v /tmp/mft-  --no-sig-check
esxcli software vib install -v /tmp/nmst-  --no-sig-check

Notice the –no-sig-check - this is required since the certificate that these were signed with are too old

Reboot the server and then the mellanox tools are located in /opt/bin/mellanox

Configure the cards to not use SRIOV - exchange 02:00.0 for the actualy address where the mellanox card is located - you can see this in the hardware list on your ESXi server.

/opt/mellanox/bin/mlxconfig -d 02:00.0 s SRIOV_EN=0 NUM_OF_VFS=0 LINK_TYPE_P1=4 LINK_TYPE_P2=4

Reboot the server

After that it should be as simple as adding a dynamic target for the iSER iSCSI adapters and remember to also add a vmkernel port binding

If you are lucky and your switch/SAN devices is configured correctly then you should see storage devices that are the iSER targets.