Late now, I already bought everything.
Is ZFS really so heavy that 8GB can't handle a media server,torrent and a VM with 512GB of ram?
The rule of thumb for ZFS, which is pretty accurate at small array sizes, is 1GB of RAM for every 1TB of hard drive space (raw HDD space, not usable). Assuming you're looking at 4x 4TB drives, I'd be aiming for 16GB of memory for sure.
On top of that, Plex can be fairly demanding, depending on how you use it. If you do any kind of transcoding with Plex, I'd recommend a beefier CPU, and again, more memory.
You mention a VM for a mail server. What OS are you thinking about here? And what software? If you're looking at some variation of Linux, most likely the software package you're thinking about using has been ported to FreeBSD, and you could run it in a FreeBSD jail (which will be much less resource intensive than running a full VM).
NAS with 2 RAID1. I already have a raid1 made with 2 WD caviar red 4TB, I want to add an other one next year
When you say that you "already have a RAID1", what do you mean? In FreeNAS, you want ZFS to manage all RAID functions. This means that any existing drives you have (unless they are already ZFS), will need to be reformatted by FreeNAS in order to use them. In other words, you'll need to backup the data on your existing drives before you can use them in FreeNAS.
Furthermore, ZFS does not use the same language to describe RAID as typical hardware RAID setup. For example, ZFS does not have RAID1; they have mirrors. The precision in language here is important, because it prevents confusion between ZFS doing the redundancy (good), or the underlying hardware doing the redundancy (bad). Cyberjocks presentation (
https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/) is a fantastic read for people new to the world of ZFS.
A lot of people here use motherboards other than SuperMicro. However, what very few people do is use consumer motherboards for FreeNAS. This is driven by a few factors: (1) they rarely (if never) support ECC memory, which is viewed largely as a requirement around here*, (2) they don't always have the best FreeBSD support, which means they can have weird problems that can be nearly impossible to resolve, (3) they come will all sorts of unnecessary hardware, like audio, that has been known to cause problems, and (4) of the hardware you do need, like your NIC, they often times use less-quality NICs that run in to problems for NAS applications.
*The view towards ECC is, in my opinion, a reflection of the fact that ZFS is about the best thing out their for data security. However, if you view your data as "expendable", then there's really no good reason to use ZFS in the first place, considering its outrageous system requirements. Obviously, there are people out there who fit in the middle, but from my experience here, and seeing the horror stories of people desperately trying to get back lost data that originally was "replaceable", most people are looking for the data security ZFS provides, and the cost difference to go with an ECC solution is minimal (usually no more than ~$150 for the better motherboard and RAM).
