need help on system build

[jbates58]

hello all.

i am trying to plan a build for my freenas system, and i had planned on selling my backblaze pod, and downgrading the chassis, but that fell through. so im going to keep and use it. it has the sas upgrade kit in it, so all drives are sonnected with sas.

i know that i probaly wont fill the chassis, but would like to buy hardware that will support it expanding as i need it.

i currently have 15odd 3TB drives and a few 6TB drives.

at the moment, im not to concerned with the setup of the pools, just the mobo, cpu and ram selection.

the use for this system will be

• backup system for phones laptops etc...
• plex server
• sync from seedbox
• media storage and streaming via plex

and thats about it.

so, with that in mind, and i know that its a piece of string question, but how much ram will i actually need? keeping in mind that i dont want to hit a ceiling that performs poorly with access times and speeds. but i dont think that im going to need the 400GB of ram for my use.

i am wanting to buy hardware that will suit, without over-doing it. i am so lost in what would be the best choice for it. and i dont want to spend a fortune unnecessarily.

some suggestions please?

Jason

 

[Robert Trevellyan]

The rule of thumb says about 1GB of RAM per 1TB of storage, with an 8GB minimum. However, the more RAM you have, the looser the rule. You might be OK with a lot less than 1GB per TB, depending on usage patterns. So, if you filled all 45 bays with 3TB drives, you'd probably want between 64GB and 128GB of RAM, but there's a chance you could get away with even less, depending on workload. The thing to do is make sure the mobo can support the most RAM you could ever need, but start out with less, buying large enough sticks to keep some slots free, and see how it performs. Also keep in mind that other key components like NIC and HBA will make a difference. If you'll be transcoding with Plex (or encrypting, but don't do that), CPU will make a difference too.

 

[jbates58]

Yeah, i have been looking into this for a while. But not to keen on spending $$$ on a board that supports 500gb of ram. If i will get away with 64. If that makes sence.

What would you expect to need with the workload i provided?

Jason

 

[Robert Trevellyan]

not to keen on spending $$$ on a board that supports 500gb of ram. If i will get away with 64

Totally understandable. However, if you want a system that can support a massive pool, you may not have much choice. In the end, the cost of the mobo will be small compared to the cost of drives if you fill that box. Also keep in mind, you can always spec it for a 3- or 5-year data growth expectation and then replace components as needed.

What would you expect to need with the workload i provided?

Sorry, not enough information. Number of simultaneous users, transcoding or not, media specs, vdev layout, so many factors, and I'm far from being an expert. The only way to know for sure it to test it with realistic workload.

 

[Darren Myers]

i think @cyberjock has ~40 some Tb with 32Gb of RAM, so some of it is a loose rule....just dont go toooooo low lol. The biggest thing we'd need to know is a budget for motherboard, cpu(s), RAM, and misc stuff like boot device and such

 

[cyberjock]

I have about 50TB of data and 32GB of RAM. The catch is that I am a single user and performance is important but not entirely paramount. I will tell you that if you don't have enough RAM performance will suffer, immensely. When I had 16GB of RAM and about 25TB of data performance was terrible (throughput for me was 1-2MB/sec)... :(