az_pmem_reserve_pages error when starting Zing

What to do if Zing 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 2MB pages and 4MB pages for Zing to start up. This might be due to memory fragmentation. 

Since Zing ZST 5.21.4 this situation is resolved much better with Zing automatically. Please consider upgrading the Zing ZST component, available for download on https://www.azul.com/software-downloads-and-documents/.

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