Really 1GB of RAM per TB - seems excessive?

[zenorb]

Hi

I'd like to build as higher density NAS box for low reasonable cost as possible.

Found a case that takes 13 x HDD so looking at 30TB+

Do I really need 32GB of RAM for this?

As per section 1.1.2 of User Guide -

1.1.2 RAM
The best way to get the most out of your FreeNAS™ system is to install as much RAM as possible. If your RAM is limited, consider using UFS until you can afford better hardware. ZFS typically requires a minimum of 6 GB of RAM in order to provide good performance; in practical terms (what you can actually install), this means that the minimum is really 8 GB. The more RAM, the better the performance, and the Forums provide anecdotal evidence from users on how much performance is gained by adding more RAM. For systems with large disk capacity (greater than 6 TB), a general rule of thumb is 1GB of RAM for every 1TB of storage.

 

[ProtoSD]

Ugghhhh..... maybe DOS would be a better choice. Why do people think this is just some arbitrary number that doesn't apply to them and the documentation full of BS? RAM is cheap, what's the point of risking your data because you think its excessive. Forget the 13th drive and get the RAM. If you spend some time reading the stickied posts, you should also discover why 13 isn't recommended and you might discover the "anecdotal evidence from users" about why RAM is important.

 

[zenorb]

OK. Thanks.

So I may need 64GB for a large 22 x 3TB (14 internal plus 8 external via eSATA if supported) config or I maybe 32GB will do?

I can fit 64GB on the LGA 2011 8 RAM slot motherboard if it works with BSD - unknown at this stage but unfortunately looks unlikely as supported motherboard list is very small.

Quite hard to get an ideal configuration with modern components.

 

[zenorb]

This really isn't as pleasant as I'd hoped.

I provided evidence that I had done my homework in the original post even quoting the relevant manual section. Have also broken questions in to hopefully helpful small and manageable chunks for anyone else wanting to consider FreeNAS with modern components such as AMD FM2 or Intel LGA2011 chipsets which I'm sorry to say I am still unclear if they are supported reading the official FreeBSD Hardware guide - that's why I asked - as it's reassuring to have help from someone who knows for sure. I'm looking at spending many thousands of dollars and would like to make a large size configuration getting the mix of case space, RAM slots, socket chipsets, JBOD controllers, and SATA ports correct.

 

[ProtoSD]

Sorry we've jumped on you so hard. When you've spent as much time here as Noob and myself, it really does get old seeing the same questions repeated almost daily and then when stuff gets documented so everything is nice and neat for people to read, people disregard it and ask again like we were just joking the first time. Anyway, I'm sure you get the idea.

Hardware changes so quickly its hard to keep or know where to update everything. FreeBSD is kind of sloppy in a lot of respects and not as well organized as some of the other distributions.

It's likely your components will work, but you may just have to just buy it and try it and return it if it doesn't work. That's how most of us learn if something works or not.

From the time I've spent in these forums, I can say that a good 90% of questions I've seen posted have been answered more than once and some significantly more. I don't recall seeing anything about those specific components, but I'm sure with a little research you'll discover some alternative options.

Cheers

 

[jgreco]

You know, the funny thing is, at one point the suggested hardware section was too terse about this topic. It still isn't overly wordy, but having just gone to re-read it now, what's there now is really a very concise summary.

Can the two of you please join me for a few moments in actually reading the Hardware_Recommendations because while they're generally sufficient, I think the OP's question of "do I really need this much RAM" is poorly addressed. Something to the effect of "If performance is not an issue, FreeBSD's ZFS implementation is known to work with as little as 1GB with a single disk. If using multi-terabyte hard disks, a FreeNAS system with 1GB of RAM per installed hard disk is about as small as it is practical to go. However, because FreeNAS ships with settings designed for performance, significant tuning may be required, and performance is expected to be poor."