Guidance requested on new build.... 8gb RAM baseline or additional per TB??

[lithium381]

I've scoured the documentation and for the life of me cannot find clarification of this...

I know 8gb is the minimum; there is also a general rule of thumb of 1gb of RAM for 1tb of storage. My question is simple: Is the 8gb JUST for the system and then an additional 1gb RAM/1tb Storage on top of that, or can I build a system up to 8tb using just 8gb of RAM and be okay? Is this guideline for raw space, or useable?


Proposed build:
HP DL320s [1x Xeon 3060 (Dual Core 2.4), 8GB DDR2 ECC] with 12 drive bays.

Populate with 12 x 1tb @ RAIDz3 for a total of 9TB of usable storage, give or take. Will I be okay with 8gb of RAM? I don't need performance, just stability. Planned use is to store a lot of jpg/raw files from my camera, a backup for my laptop, and likely a VMWARE nfs datastore for my home lab. How miserable would I be if i went with 2tb HD's instead? 18tb storage with 8gb ram? This is the maximum memory the motherboard can handle.

 

[Steve Lumponalog]

Hi Lithium,

Great question, and one that frequently crossed my mind before I read Cyberjock's guide. You can get the guide here:

http://forums.freenas.org/threads/slideshow-explaining-vdev-zpool-zil-and-l2arc-for-noobs.7775/

On page 35 of the PDF, you'll find:

If you want to use ZFS with less than FreeNAS’ recommended RAM you should consider the NAS4Free project. NAS4Free recommends 1GB per TB of storage without the baseline 8GB. So if you have 5TB of storage you’d need 13GB of RAM for FreeNAS, but only 5GB for NAS4Free. Note that using NAS4Free does not alleviate the risk of improper shutdowns crashing your system. So don’t lowball your RAM needs. ​

Admittedly, this is a bit of an internet backwater reference. Unless Cyberjock is wrong (unlikely: he's an amazing and generous resource), you'll be best off with 17 GB of RAM for a 9TB system, though the system should function with 8 GB RAM.

If you are now considering a different motherboard, Cyberjock has a guide for that, too:

https://forums.freenas.org/index.php?threads/hardware-recommendations-read-this-first.23069/


Steve.

 

[enemy85]

You will be "ok". The 8gb are the minimum requirement for stability and SHOULD be fine with 8-9tb. Of course with many services/users/jails running on freenas your performances COULD not be at the top, but at least you will not have stability problems. Of course if you go with 2tb hd it will be better to use 16gb of ram.

 

[lithium381]

The motherboard maxes out at 8gb....
I plan to have only three USERS[two of which will probably just do a backup once a week or so via rsync or timemachine] + my VMs.... based on what i've read i have no intention of running a jail. services will likely be limited to NFS since we're on Macs and my VMs prefer NFS as well..

so the question becomes will i lose data @ 18tb w/ 8gb ram.

Thank you for your replies thus far!

 

[danb35]

Will it work? Probably. Will you lose your data? Most likely not. However, your system really isn't optimal, and you shouldn't expect great performance. Part of that is due to the amount of RAM, but even more than that, the speed of RAM and the processor's FSB.

 

[L]

The way that data can be lost is to run non-ecc ram. If you run into problems the solution isn't nas4free, it is to just go to raw freebsd. I have run freebsd with systems as low as a single GB of ram

 

[lithium381]

Thanks, guys. I made sure to get ECC RAM. I know it'll be a dog on performance, but right now i just need a place to park data, i don't expect a lot of high intensity IO. I've got my FTP server running on Ubuntu and i've pushed that one as low as 128mb and still been okay...

 

[cyberjock]

The way that data can be lost is to run non-ecc ram. If you run into problems the solution isn't nas4free, it is to just go to raw freebsd. I have run freebsd with systems as low as a single GB of ram

Linda, you are 100% correct. But the vast majority of people that are here have never touched a FreeBSD command line. So an OS with at least something resembling a GUI (like NAS4Free) gives them a chance of running a FreeBSD-based server. ;)

 

[L]

If you want to only have 1-8GB of ram.. then you better learn the command line :) Otherwise spring for more ram. It can either be easy or cheap, but it can never be both :)

The other thing I have found on this forum is there are a lot of people who have used a command line unix too.