ESXi upgrade preparation
With Cisco UCS you really need to make sure that your ESXi hosts are running the correct driver version. If you’re running NFS or FCoE storage into your ESXi hosts as either datastores or RDM disks then it’s critical that you have the right fnic and enic drivers. Even if you use the Cisco Custom image for ESXi upgrades the enic and fnic drivers may not be correct according to the compatibility matrix. I’ve had this issue in the past and I saw intermittent NFS datastores going offline for a Dev ESXi host and the resolution was to upgrade the enic driver which handles ethernet storage connectivity.
The best place to go is to VMware’s compatibility site for IO drivers which comes under the System/Servers. To find out which drivers you currently have you will need to check on the driver versions on the ESXi hosts. This can be done by following KB1027206. Using the values for the Vendor ID, Device ID, Sub-Vendor ID and Sub-Device ID it’s possible to pinpoint the interoperability with your respective hardware. In my case I have both VIC1340 and VIC1240 in the mix so I had to go through the process twice. Primarily you’ll be using the ‘ethtool -i’ command to find the driver version.
e.g. You can check the UCS VIC 1240 for FCoE CNAs on ESXi 5.5 Update 3 here
In this image you can see the version of enic drivers I’m running, 126.96.36.199 doesn’t match the firmware version that will be installed as part of the Cisco Custom ISO image. This shows that the enic driver version will need to be upgraded as part of the process.