I have been running OMV 3 on a Raspberry Pi model B for about 2 years. It has been running great -- very slow throughput, but solid as a rock and more than fast enough for my home NAS needs.
I recently got a Raspberry Pi 3B+ and decided to upgrade to OMV4. Getting it set up and running was fairly painless, and I was immediately seeing a five-fold increase in throughput (from 2MB/s to 10 MB/s)! BUT, when multiple devices are accessing the device (one downloading and one copying a file, say, or copying a file remotely and doing an rsync --dry-run locally), the throughput drops to 0 after a few seconds and remote devices trying to access get an unexpected network error. I assume that OMV isn't feeding data to the connection for long enough that the network request fails, because retrying always works for a few seconds before failing out again.
I have read most of @tkaiser's posts (thanks for the info!) on the RaspBerry Pi and know that it is "the worst SBC" for running a NAS. Point taken. However, it's what I have access to. Since the model B (1 core, 512MB ram) works really really well even when I have 7 or 8 devices streaming from it, and the #B+ (4 cores, 1GB ram) seems to choke on multiple streams, I'm assuming that somehow OMV4 has been optimized to pretty much use everything it can get up to a certain point (I realize this could be very wrong, and would love to hear other thoughts). So:
>>Is it possible in some way to 'cripple' omv 4 so I can keep it's speeds below what the 3B+ can handle (interesting the load never goes past 3 in the performance statistics)?
>>Am I completely off base and should be looking in a different place for trying to fix this?
>>Barring that, anyone know where I could find an OMV3 Image for the RaspBerry Pi that works like the omv4 image created by tkaiser? Or should I just try to install it manually through a distribution of Raspbian stretch?