I tried searching to see if this has already been covered, but wasn't able to find much. Sorry if this is covered somewhere and my search skills were bad.
BottomLineUpFront: I am getting ready to install OMV 5 and trying to decide whether to use RAID5 or SnapRAID. An important use case for me is to support using the OMV data drives as a network target for Apple TimeMachine backup. Is one choice better than the other for TimeMachine?
Detailed and probably too long background info:
I have been successfully using a VERY old version of OMV (1.19 Kralizec) for over 5 years now. It has served me well, but I want to upgrade to a newer version now. I realize that upgrading from 1.19 to 5.x isn't really a thing, so I have purchased a new OS disk and new (also larger) data drives, and will start with a fresh install. I will take my existing OS and data drives out of the machine and start with new ones to install OMV 5. After installing, I will load data onto the new OMV from my nightly backup disk (which is a single large external disk mounted over USB and different from the data disks I will be taking out of my existing OMV build). The new data drives will be four 4TB Seagate NAS Drives (I bought Seagate because (a) the 2TB drives in my current build have served me well for 5 years and (b) I have read bad things about WD NAS drives and SMR write, so Seagate seemed like a good choice).
I don't really use OMV as a media server, but rather it is mostly just a big disk that serves as a target for Windows backup programs running on a couple of windows machines, and as an AppleTimeMachine target for four MACs in our house. I also have a couple of "sideband" things running on the machine - specifically it runs cups to serve as a print server, and it runs my UniFi network controller software that handles my networking devices.
My old NAS configuration used RAID5. For the OMV 5 installation, I am trying to decide between RAID5 and SnapRaid + UnionFS. I will have three data disks and one parity disk in either arrangement. Because I mostly use it as a target for backups of other machine (and it is then backed up nightly to one of two portable disks that gets swapped to offsite storage approximately monthly), I guess I don't really have to use a UnionFS to make it look like one big store, but I kind of like the flexibility.
My question is this: Does anyone have any experience that would suggest whether AppleTimeMachine might work better with one solution or the other (RAID5 vs SnapRaid+UnionFS)? If so, which one is better. I realize SnapRaid (and netatalk for that matter) are plugins and not directly built into OMV, so maybe I'm asking this question in the wrong place. If so, please let me know. In case it matters here, all of my disks (OS and Data) will be spinning disks - none are SSD.
I have also read that you can now set Apple computers to target a disk over SMB (CIFS) with the right settings, and that OMV 5 supports this, so I guess that might also be a consideration.
Any advice is appreciated. I have all of the hardware ready to go and will likely start the install this coming weekend (July 4/5, 2020).
Thanks in advance!