This system is overpowered in some ways, and under-powered in others. I'm assuming that whichever country you live in is giving you some limitations on hardware, in which case, some of my recommendations would be inappropriate.
Mainboard: ASUS PL11C-C/4L including KVM
I think you may have the model number wrong here. I believe it's P11C-C/4L (no "L" after the "P"). In any event, this is a heck of a motherboard to pair with only 16GB of RAM and an i3 processor. Is there a reason you've gone with this motherboard instead of, say SUPERMICRO MBD-X11SSL-F-O? Or even the P11C-M/4L?
Memory: 2x 8GB DDR4 UDIMM ECC 2666MHz
CPU: Intel i3-9100F (no graphic)
Both compatible with the chosen motherboard. You could probably go previous gen and save some money all across the board.
Disks:
- 2x Samsung NVMe 970 Evo Plus 512GB (mirror - jailhouse pool)
- 2x WD Red Pro 8TB 5400RPM 256MB ( mirror - data pool)
- 2x Samsung NVMe 970 Evo Plus 256GB via USB 3.0 (vdev cache for data pool)
- 1x SanDisk 128GB (SSD tech) via USB 2.0 for boot/system
You have some interesting choices here.
First the jail pool: an SSD mirror should do fine for jail storage. However, given that all you're doing is Nextcloud, this is really overkill.
Data Pool: good call on the Red Pros. Make sure you avoid the SMR problem! However, the choice of an 8TB mirror is interesting. Right now, it looks like 4TB drives have the best price/TB ratio, so 3x 4TB drives in RAIDZ would give you as much space as your 8TB mirror for much less cost. Scaled up, you could probably do 5x or 6x 4TB drives in RAIDZ2 for slightly more, with now double redundancy, and even more storage space.
"vdev cache": Wrong, wrong wrong! Nothing about this makes sense. First off, let's clean up the terminology. A cache vdev adds read cache to a pool. Often, this is referred to as an L2ARC drive, because it provides level 2 ARC (adaptive replacement cache; the main L1 ARC is your RAM). L2ARC is only beneficial in certain circumstances. Most importantly, if you are reading a file many times, an L2ARC can help a lot. But if you are reading data randomly, an L2ARC does nothing. Furthermore, it could actually make system performance worse, because RAM (which would be L1 ARC) is now being used to manage your L2ARC. For media streaming, an L2ARC is almost useless.
So, here's the issue: you're listing two drives to be used as L2ARC devices. For your use case, you don't even need one drive. 2nd: what the heck are you doing connecting these drives through USB3!? You have SATA ports on your motherboard. Use them! These drives are a waste, versus buying more data drives for your main data pool.
Perhaps, you really meant that you wanted to use one of these as a Log device, or a SLOG (separate log). That might help you, again, depending on your use case. Connecting it through USB 3, though...that's just setting you up for a bad time.
If you did mean to go the SLOG route, then these drives are not exactly the right devices. ZFS only uses something like 4GB max for its SLOG. A good SLOG devices is a highly reliable SSD with power loss protection. If you're serious about data protection, then you should probably mirror the SLOG. If you don't care about data protection, then don't do sync-writes to your NAS.
With your use case of Nextclound and media streaming, you won't benefit from a SLOG either.
boot/system: I don't know what your boot device is. Is that a USB stick or an SSD? 128GB is way overkill for a boot device. You're way better off with 2x 16GB USB sticks in a mirror. If it's an SSD, just use a SATA port and be done with it; none of this SATA devices via USB nonsense.
---
Overall, if this was my system, I'd look at the following changes:
- Buy last-gen hardware to save a $100 or two.
- Lose the cache devices, and giant SATA drives, and buy 6x 4TB drives. Run those in stripped mirrors for performance, or RAIDZ2 for space.
- Get mirrored USB sticks for the boot device.
- If you really only plan on doing Nextcloud, lose the jail pool and spend that money on an extra pair of 4TB SATA drives.
