I have OMV running on a QNAP TS-451 and it works well. I did upgrade the flash memory on the motherboard to 8 GB and the ram to 8 GB as well. You don't have to upgrade the ram but it helps. You can't install OMV on the 512mb flash memory but you could plug a flash drive into one of the usb ports. After that, the device is almost the same as any intel system.
Hello
gently
how did you upgraded the FLASH DISK to 8GB?
Using a USB stick instead? Like this guide --> https://forum.qnap.com/viewtopic.php?t=133899
Thank you