Since my ESXi hosts are upgraded to VMware vSphere ESXi 6.5, the vmkernel.log is constantly spammed with warnings reporting that the physical block size from my LUNs, provided by a FreeNAS storage, have an unsupported block size.
WARNING: ScsiPath: 4394: The Physical block size "131072" reported by the path vmhba64:C0:T4:L0 is not supported. The only supported physical blocksizes are 512 and 4096
WARNING: ScsiDeviceIO: 6462: The Physical block size "131072" reported by the device naa.6589cfc0000000572b71f35019e9c31f is not supported. The only supported physical blocksizes are 512 and 4096
I'm using FreeNAS-9.10.2 with iSCSI LUNs backed by a ZFS volume. The physical blocksize is reported as the ZFS recordsize which is 128K by default.
[root@freenas01] ~# zfs get recordsize flash NAME PROPERTY VALUE SOURCE flash recordsize 128K default
To get rid of the warnings, activate "Disable Physical Block Size Reporting" in the iSCSI Extent configuration.
Sharing > Block (iSCSI) > Extents > Edit > Disable Physical Block Size Reporting