Users Guide

ESXi troubleshooting and maintenance

NOTE: Go through /var/log/vmkernel.log to see if there are any errors or warnings reported related to persistent memory.

The log entries related to persistent memory would be appended with "NVD" and/or "IntelNVDimm"

● Configuring Intel DCPMM in memory mode shows a reduction of system memory in system BIOS.

○ For example, a system configuration with 4 * 128 GB Intel DCPMMs, configured in memory mode provides a system

memory of 504 GB instead of 512 GB.

○ It is for reserving space for metadata.

● PMEM datastore is not mounted automatically in ESXi.

○ See /var/log/vmkernel.log and check for ‘shut down counter’ related errors to DIMM handles.

○ When there is a critical error to any of the Intel DCPMMs, datastore is not mounted by ESXi.

● ESXi boot takes longer when Intel DCPMMs are configured as Non-interleaved App-Direct. Dell EMC does not support

Non-interleaved App-Direct goals with ESXi.

● If DCPMMs contain a critical error, the ESXi Host Client (HTML client) GUI does not respond when the user moves to

Persistent Memory section under Storage. The host server is unresponsive when it reads the PMEM region address range

with the critical error. For more information see VMware KB 70661: https://kb.vmware.com/s/article/70661.

● In ESXi, Windows as a guest operating system does not display Storage Class Memory device in the device manager, for the

PMEM devices that are attached to the virtual machine (VM).

Virtual BIOS for the VM hides the device from device manager. User can use the PowerShell cmdlets to view the PMEM

devices that are attached to the windows guest operating systems running on ESXi.

● ‘esxtop’ utility in ESXi exposes some dummy performance counters when DCPMMs are configured in the system. Counter

names might be displayed as ‘Cache hit’, ‘Cache miss’, ‘nBuffers’, ‘Flush interval’. These are dummy performance counters

and no functionalities that are associated with it for now.

● ESXi displays more number of NUMA nodes on systems that are configured with DCPMMs in App-direct mode. This is an

expected behavior as the NUMA nodes are created for volatile and nonvolatile address ranges. The nonvolatile address

ranges are displayed as 0 MB.

● ESXi logs a warning in the Vmkernel log 'Unable to register PMEM file system for APD notifications'. This log entry can be

safely ignored as the PSA (Pluggable Storage Architecture) APD(All Paths Down) plug-in is not supported for PMEM type

volumes. For more information see VMware KB 2145444: https://kb.vmware.com/s/article/2145444.

VMware ESXi