Does FreeNAS really need 8Gb of RAM?

[Neth]

Hi!

What's your experience when it comes to RAM usage for FreeNAS?
I'm new to FreeNAS, but when reading different articles etc on the internet I've understood that FreeNAS "needs" 8Gb of RAM to funtion properly. However, now that I have FreeNAS installed and check the memory usage under Reporting it shows that it hardly uses 2Gb of RAM, even when streaming a FullHD movie.

I have 8 Gb of RAM in my server on which I am running FreeNAS. I decied to not run any virtualization or such since FreeNAS alone needed all my RAM. But now I'm not so sure....

So. what's the experience on the board - is 8Gb RAM really needed?

Edit: Adding Image

 

[mav@]

All loads are different, and 8GB is average safe-side recommendation. There were rumors that somebody managed to run ZFS on 32-bit architecture with 256MB of RAM, but it does not mean you can run any serious server with that. FreeNAS itself uses not so much, depending on number of enabled services. But ZFS requires RAM for caching, that is critical for performance. If memory is not enough to store all required metadata, then data access becomes slower. On systems with less then 4GB ZFS by default completely disables prefetch, that significantly reduce performance. Sequential file read in your example is hardly a serious load that requires or can really use much RAM, but there are other much more complicated loads.

 

[joeschmuck]

What period of time you are showing us is very small, 1 hour and you rebooted in that period of time it looks like. Change the period to 1 week or 1 month and lets see the results please.

As to the question you asked, FreeNAS will run fine on 6GB of RAM in my opinion however 8GB is the default safe lower limit to avoid RAM shortages when people start loading Plugins and extra jails. I'm not sure I understand what you mean by not running any visualization, if you mean not running jails or not running FreeNAS on a virtual OS.

 

[Fuganater]

How much storage do you have? I have 10TB and I am using 7GB of my 8GB RAM.

 

[pirateghost]

yes, you need it.

 

[cyberjock]

I've done several one-on-one scenarios with various people in the forums that had things not working right. Things as simple as zpool creation, updating the OS, and other things you'd expect to "work" don't work with 6GB of RAM (no RAM for the video card allocated). They upgraded to 8GB and it suddenly started working.

So yes, 8GB is the mininum.

 

[Neth]

Thank you all for your replies.

I guess the answer stands clear, 8Gb is needed to ensure proper functionality. The main reason being ZFS.
That ensures me in my decision, I'll just keep going with running only FreeNAS and nothing else (ie. no virtualization) on my setup - which has just 8Gb of RAM.

Sidenotes:

What period of time you are showing us is very small, 1 hour and you rebooted in that period of time it looks like. Change the period to 1 week or 1 month and lets see the results please.
...
I'm not sure I understand what you mean by not running any visualization, if you mean not running jails or not running FreeNAS on a virtual OS.

True, I have only been running FreeNAS for a couple of days and have had to reboot several times and even reinstall the OS due to problems with CIFS. I've got another thread for that issue, see link below:
https://forums.freenas.org/index.ph...for-usr-pw-although-guest-access-is-on.38630/

By virtualization i mean running for ex ESXi,

How much storage do you have? I have 10TB and I am using 7GB of my 8GB RAM.

I have 4x2TB disks which gives me 5TB available storage space in my RAID.

 

[DrKK]

How much storage do you have? I have 10TB and I am using 7GB of my 8GB RAM.

Just for the record, that's by design. In FreeNAS, generally speaking, it's set so that the ZFS MFU/MRU ARC will consume all of your RAM pool minus 1GB, just as a reserve.

 

[Fuganater]

Just for the record, that's by design. In FreeNAS, generally speaking, it's set so that the ZFS MFU/MRU ARC will consume all of your RAM pool minus 1GB, just as a reserve.

Ah good to know!

Sent from my SM-T700 using Tapatalk

 

[JJT211]

Give it a few days or even a week. ZFS takes some time to start utilizing all the RAM it needs.

Simultaneously transcode a few videos if you wanna see it spike up faster.

 

[Neth]

Yep, you are correct. Checked the Reporting -> Memory today and all RAM is now being used. :)

 

[joeschmuck]

I figured it would eventually jump up and if it didn't, then I'd want to know what you are doing to keep RAM utilization so low :)

 

[wreedps]

I have 192GB and its "alright"

 

[jgreco]

I originally boosted the minimum memory from 6GB to 8GB in response to repeated frequent issues people had here in the forums with really bad things happening on smaller memory configurations. It isn't clear that those same problems exist any longer, but on the other hand, 8GB of RAM is not particularly expensive any longer and there's still a lot of anecdotal evidence that smaller configurations are problematic.