az_pmem_reserve_pages error when starting Azul Zulu Prime JVM

What to do if Azul Zulu Prime JVM fails on startup with an error message like this:

ERROR: az_pmem_reserve_pages (num2mPages 193811)
Fatal error: os::safeSystem: command '/usr/sbin/zing-llpmem --reserve --partition 0 --pages 193811 --nodemask 0xFFFFFFFF' failed.
zing-memory: ERROR: Configure pmem failed
Fatal error: os::safeSystem: command '/etc/init.d/zing-memory restart' failed.

The most likely cause of this error is that there is not enough free RAM on the system, specifically, there are not enough free large pages (2MB or 4MB) for Azul Zulu Prime JVM to start up. This might be due to memory fragmentation. 

Since Azul Zulu Prime System Tools (ZST) 5.21.7 an optional configuration is available to resolve this situation. Please consider upgrading the ZST component, available for download on https://www.azul.com/software-downloads-and-documents/ and if needed, enable the additional configuration as described on the following page: https://docs.azul.com/prime/ZST-Enhanced-Linux-Memory-Defragmentation

Since Azul Zulu Prime JVM 19.07, Azul Platform Prime can also be installed and used without ZST. In that mode it does not need large pages and uses standard 4k Linux pages instead and won't be affected by memory fragmentation.

On older ZST versions the fastest way to try to fix this is to reboot your machine.