Does ECC ram need to be installed in pairs? Most of what I'm seeing is single modules. Makes me think I should use 1x8gb rather than 2x4gb.

There's no requirement to install it in pairs; but if you're using a system that supports dual channel memory access, you'll get a higher memory bandwidth if the modules are installed in pairs.

 

However ... assuming you're using unbuffered modules, you should also consider that it's best to not install more than a total of 2 modules.    So if you plan to increase your memory beyond 8GB, I'd just buy a single 8GB module now, and then add another one when you want to increase your capacity.

 

Thanks. Right now I'm still exploring possibilities regarding motherboards. Mainly ECC or standard ram, but I'm sure it will have dual channel memory access. Just not sure about single/double and 4gb/8gb. Do unraid systems typically need more than 8gb of ram? If 16gb isn't likely to be needed I might do better to get 2x4gb.

As UnRAID moves to 64 bits (with v6) it's likely that both the core NAS and certainly the various add-ons will take advantage of the increased address space, so there will indeed be benefits from having larger amounts of RAM.  I've installed 16GB (2 x 8GB) in all of the recent systems I've built (UnRAID or otherwise), just to be sure there was plenty of "headroom" for future growth.

 

If you plan to use UnRAID as just a NAS, and aren't going to use any of the virtualization features added by v6, then 8GB is plenty.    Otherwise I'd plan for 16GB.

 

Thanks again. I may never use the VM features but I've been trying to keep the door open for them. Looks like I'll go ahead and plan for 2x8gb ECC.