Symptoms:

After upgrading from an earlier ESXi  7.0 release, previously created NVMe / RDMA namespaces and datastores are no longer visible in the vSphere Client. 

In the vmkernel.log, you find the following warning:

(...) WARNING: NVMFVSI:861 Invalid admin queue size 16

VMware vSphere ESXi 7.0.3

In prior releases, vCenter will set the admin queue size explicitly to the default value 16, which is stored in configstore on ESXi as an attribute of an NVMe-oF connection which is used to restore the connection when rebooting.

In 7.0 U3 (c,d and e), in order to support additional NVMe features, the default admin queue size was increased to 32. vCenter also no longer specifies the admin queue size, thus ESXi can use whatever default admin queue size it had previously set.

Since the stored value of 16 is no longer valid after the reboot, NVMe-oF connections are not restored after the upgrade.

This issue is resolved with ESXi 7.0 U3f

Workaround:

To work around this issue on ESXi releases before 7.0 U3f, use the attached python script to change the admin queue value in configstore:

# python ./kb_88938_script.py