virtual memory vs physical memory

[nteeple]

i believe cloudlinux allow us to specify how many virtual memory and physical memory can be assign to one account. my question is, can i set virtual memory to unlimited which i can set as 0 in the ve.cfg and physical memory to 2 or 3 GB? if this can be done.

1. what will happened if the pysical memory has been fully utilize?
2. will the unlimited virtual memory i set just now will affect actual physical memory which i install on the server?
3. is there any specific calculation that i can use to calculate the maximum concurrent connection that my server can handle.

please advise.

[iseletsk]

You can set virtual memory limit to 0, and use only physical limit.

1. When all the physical memory gets utilized for a user, same thing happens as if all the physical memory would be utilized for the system: First disk caches for that user will be purged, after that OOM would kill processes for that user -- to make sure there are some available memory
2. Virtual memory limits will not affect physical memory limits.
3. Not that I know, but it cannot be more then MaxClients set for apache server.

[ahmadfaizall]

hi igor,

thanks for your prompt reply. btw, i would like to get some recomendation from you. if i have PHP and mysql running inside the server. can i run apache MPM worker? cause from my understanding prefork is using a lot of memory. and i scare that i will loose a lot of memory if my server have more than 1000 concurent connections.

Please advise.

[iseletsk]

You can run Apache MPM Worker, as long as you don use mod_php
Apache MPM Worker is fully compatible with mod_fcgid & mod_suphp.
MySQL will not interfere with apache in anyway