Memory consumption and virtual machines

[anderstn]

Hi

So after seeing my memory spike drastically after I wrote some files to my first RAID array I was worried I had done something wrong. As it turns out this is really just the effect of a pretty neat feature that caches written data in memory. This however raises another question. What happens if I start creating virtual machines or jails on the server. Will FreeNAS just automatically ensure that there are no memory conflicts or do I have to do something to indicate to the system how much memory I want to reserve for other purposes than caching files?

 

[MrToddsFriends]

It is possible to give a limitation on the amount of memory to be used for ARC using the vfs.zfs.arc_max tunable, but usually not necessary (well, maybe if you see unwanted swap usage).

http://doc.freenas.org/11/system.html?highlight=tunable#tunables
https://forums.freenas.org/index.php?threads/vfs-zfs-arc_max-has-immediate-effect.55768/

 

[anderstn]

Thx for the reply. I assume this means the OS considers any memory consumption beyond the minimum required for arc to be of least concern compared to other running tasks like an active VM. Hence I will just leave it alone unless it causes unwanted behavior :)