FreeNAS Shuffle
When I first set up my FreeNAS server, I had no idea what I was doing. At all. This was my proverbial toe in the water of storage. I read over all the documentation beforehand, sure, but that didn't mean I knew what I was doing.
The phenomenon surrounding FreeNAS is its use of Solaris' ZFS filesystem, a hearty, replicated aggregate of both filesystem and volume manager, underneath a FreeBSD front-end. By default ZFS requires a lot of resources, which is why I put it on my beefiest box, which just so happened to be the only box I had which contained a RAID controller which could be bypassed to allow FreeNAS to carve the raw disks directly. Or so I thought. Spoiler alert, it doesn't.
So unbeknownst to me for nearly a year, my FreeNAS instance carved its volume management from the server's RAID array. Surely this would have gone unnoticed indefinitely, excepting a single drive failure. ZFS handles drive failures with aplomb - disable the drive in the NAS GUI, hot swap and rebuild. However, because FreeNAS couldn't see the individual drive (remember, it only sees the entire array), I couldn't disable it. No problem for a hot-swap RAID array though, right? Or was it?
I posted the conundrum to the local FreeNAS forums and the reply I received was, "Well, it might work, it might not." Awkwardly enough, that was my own conclusion as well prior to posting the question. Regardless, I backed up the entire array to my UNRAID server, and for good measure powered-down the FreeNAS server before replacing the failed disk. Everything booted and the hardware RAID starting rebuilding, unbeknownst to FreeNAS, and someday (not today) I'll look at migrating away from my initial architectural failure.
