RAM questions...

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Jun 24, 2017
Hi guys...

I sort of k ow the answer to this... but feel the need to ask anyway.

I currently have a dell t3500 machine, 24GB paired ram, 20TB (4x5TB) Seagate drives... x5667 xeon processor. I run the NAS storage as NFS access across my internal network. I also run jails for sonarr, couchpotato, sabnzb, transmission (with PIA vnc), and owncloud... I also run a VM to host zoneminder... I am moving the entire system to a t7500 w/ the same processor, and swapping out the ram for ECC ram (and maxing it out probably... at 192gb... I just have it laying around anyway)

Looking at my statistics, I've never used more than 14GB of ram in the current rig... is there ANY benefit to increasing the amount of ram that the system uses? (Mind you, not having a benefits wont really stop me from deploying said ram... but i may be more particular and use all absolutely identical ram... which would limit me to 96GB (12x8GB sticks)... 192gb require that i mix brands...

Sorry if thats wordy... and honestly, it breaks down to a theoretical question...

Follow up: would it, in the end, be better to run all the jails in a VM rather than individual jails? Assume security doesnt matter... or are the individual jails more efficient than something like an Ubuntu VM running everything?


Documentation Engineer
Nov 14, 2014
Jails are much more efficient than VMs. Particularly in RAM usage, because they are using the host system kernel and only as much memory as they need. VMs have to allocate a static amount of memory to run an entire operating system. Whether they will actually use that much RAM all the time or not, that's memory that can't be used by the host system.

Chris Moore

Hall of Famer
May 2, 2015
I have a T7500 with 192GB of registered ECC memory at work that I use for running virtual machines. I have the six core 3.4 ish GHz CPUs. I don't remember the model. I use Windows server and Hyper-v and it can run 8 VMs with ease.
If you wanted, you could probably put ESXi on the bare metal and put FreeNAS inside a virtual machine. Then share the FreeNAS storage with a virtual network inside the virtual space to store the other VMs on and be able to run any kind of OS you want.
You would need to add a SAS HBA to the system to run the storage drives and pass it through VMware to the VM install of FreeNAS. I don't know if the hardware pass through for a SAS controller would work on the T7500.
I know that some people have done similarly but with newer hardware.

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Feb 10, 2014
Just some feedback on my experience:
I'm going the direction that @Chris Moore described: FreeNAS on ESXi.

I have a HP DL380G6 with 2x xeon L5640 that I could fill with 176GB (ECC) RAM: I thought this is a bit too much for FreeNAS on the bare metal for a single user! ;-)
So I decided to virtualize FreeNAS with ESXi. It's a good exercice (still in testing phase), got a SAS HBA, set it to pass through in VMWare, reserved 64GB of RAM (way to much but it doesn't matter) for FreeNAS, using 4 vCPUs for FreeNAS. And still have plenty of resource for VMs.
I'm also on the way to move the jails (Plex, NextCloud) to VMs. I use (for now) Ubuntu server for the NextCloud VM. I didn't move Plex yet into a VM.
I did it much more for personal educational purposes rather than efficiency (
Jails are much more efficient than VMs.
) ;-).

I have to say, it's a lot of fun!

Regarding the ECC RAM, my goal was to maximise the RAM, so I am mixing brands (and size and probably timings.... not sure of that last one though).
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