We're running Zimbra 8.7.11 FOSS on ubuntu 14 LTS with Zextras 2.6.2
The server is an Atom C2550 w/ 16gb RAM and 4x500gb SATA drives using MD raid
Historically this configuration has been more than adequate, but having fairly recently installed Zextras and ramping up the number of ZxMobile users - its being exhausted in terms of CPU and ostensibly RAM (via out of memory errors)
There is currently only 15 devices syncing, which is a mix of Outlook, iPhone and Android.
Easing the notifications latency to 15 seconds has helped reduce the CPU usage but its still high (4x 80%+)
I have applied most of the settings here: https://wiki.zimbra.com/wiki/Performance_Tuning_Guidelines_for_Large_Deployments
Adjusting the mailboxd_java_heap_size has helped reduce the Out of Memory errors but they are still occurring roughly once per day.
Looking through the system performance statics, IO is not busy at all, CPU is very high, I keep giving java more memory wondering what the best value is?
I would appreciate peoples thoughts and recommendations.