Options for Locally Seeding a FreeNAS Pool via RSYNC to ext4 UnionFileSystem "psuedopool"

[Midshipman]

Greetings,

• I have a FreeNAS system, henceforth "Main FreeNAS", with a Pool of seven 3TB hard drives, 2 parity, with a single volume with a few datasets on it nearly full at 11.5 TB. The motherboard is Supermicro X10SL7-F with 14 SATA ports with 7 of them free at the moment.
• I have an OpenMediaVault system, henceforth "Backup OMV NAS", that currently has two USB 3.0 8TB hard drives setup as a single "pseudopool" (not sure of the official term) via Union File System. Each drive is individually formatted as ext4 via the OMV web-based interface. The system is a Raspberry Pi 2 B+. (This system is basically "spare parts" to serve as an as-cheap-as-possible backup to the Main NAS. Eventually I plan on building a second FreeNAS system and placing it offsite to replicate to.)

After 18 hours of trial-and-error, I have currently in-process a successful RSYNC via SSH from my Main FreeNAS system backing up all my data to the Backup OMV NAS.

The problem is that the system only writes at 7.5MBps . . . a Raspberry Pi 2 B+ isn't very capable. I'd prefer not to wait 3 weeks for this to finish.

QUESTION: Is there a way to get FreeNAS to locally mount the Union File System ext4 hard drives as a single "volume" for me to then locally RSYNC the files over the first time, i.e. seed them? After that first RSYNC, I'd reconnect the drives to the Backup OMV NAS system for future RSYNCS.

• If it cannot be done via USB, I'm okay shucking the drives and connecting them internally via SATA to the FreeNAS system. (I'd hope that if I then unshuck them back into their USB cases, the Backup OMV NAS could still read them.)
• If Union File System doesn't work in FreeNAS, then would two separate ext4 drives (via USB or less preferentially internal SATA) work? I don't really understand UnionFS but it *seems* that two drives could be merged with data on them later. Although I'm not sure that OpenMediaVault could recognize them . . . lot's of "ifs" here.
• Yes, OpenMediaVault supposedly can work with ZFS as well but I haven't gotten it to work yet; lots of errors possibly pointing me to having too little ram (1GB) on this Raspberry Pi. So I'd like to try to stick to ext4 if possible.

 

[sretalla]

a Raspberry Pi 2 B+ isn't very capable

Agreed. Do you have any other system with some more capability that can temporarily be used (or even a VM on another computer running whatever OS like Mac or Windows)?

FreeNAS will not play well with EXT4, so use rsync if you want to make your life simple. Setting up a linux VM on your PC and passing in USB drives isn't hard. Virtualbox is free.

 

[Midshipman]

Yes, I do have a main powerful Windows desktop machine I could use. I've never created virtual machines before so there may be some learning curve, but that sounds interesting.

I've also ordered a Raspberry Pi 4 to replace this Pi 2. Per some online research it seems the Pi 4 can saturate gigabit ethernet and USB 3.0 drives, so I might just wait until it arrives and restart the process then.

If there is no simple way to connect the drives directly to the FreeNAS machine, then one of the two options above seems the best idea.

Thanks!