We have an HP N54L Microserver running FreeNAS that has recently stopped working. In the months leading to it's total failure, it would disappear off our network and a reboot every few months usually got it back online, until recently it just dropped off completely. It was years ago that I set it up and cannot remember exactly what I put on the USB drive or how I even got FreeNAS running on it 😅. On hindsight, it probably wasn't a very good idea running the FreeNAS OS off a USB stick.
The thing now is, I'm unsure of what the problem is, I tried removing the USB stick containing the OS and plugging it into my laptop, but it says the drive needs to be reformatted. Does this mean the USB stick is corrupted or is it running a different file system? The lights on the front of the NAS and on the network port are flashing and the fans turn on, but I cannot see the NAS under "wired devices" on my router browser admin page.
What's the best way forward to test this or to get our NAS back up and running?
The N54L is pretty old now, I had one for years and it was amazing.
I've since upgraded to an AMD desktop running as a server with an HBA card (2xSAS -> 8x Drives).
If you're happy with the N54L formfactor, check out the newer HP Microservers, they're still pretty solid - but you do pay extra because it's a "server".
As for the USB coming up saying it needs to be formatted, that's normal as it's formatted for FreeBSD.
If you want to try get that machine running again, make a new FreeNAS (now called TrueNAS) USB stick and stick it in (leave your old stick as is for now) and see if it boots (Note - Use TrueNAS Core, not TrueNAS Scale - if it all works and is good you can upgrade to TrueNAS Scale later). Your RAID should be okay, TrueNAS will see it and let you reimport it. If you've got a backup of the config you can import that too and it should just keep going as it was.
Holla if you've got more questions - I love TrueNAS :D