More detail might help others help you. What kind of array did you start with? You said you "added a drive" to your FreeNAS. Do you really mean you had a failed drive, so you replaced it with a new one? What steps did you follow to do this replacement? If you go to the shell, what does "dmesg" show? What does "zpool status" show? What version of FreeNAS are you running (the whole string)? The more detail you can provide, the better the experienced guys here can help you.
I apologize for my lack of information. I was very tired last night, and had been at this problem for at least 12 hours. Anyway, I don't know what kind of array I started with to be honest. Actually, let me start with some background. I'm running this on a quad core Xenon server, on Windows Server 2008r2, and using VMWare Player. FreeNAS-8.2.0-RELEASE-p1-x64 (r11950)
I have been amassing drives for years now, and had been keeping them as NTFS, but I hated having multiple drives with multiple filesystems for organizing my media. My Media server died recently so I decided to move all the drives to a FreeNAS. I had been copying drive contents to the NAS, and then wiping and adding the drive to the NAS. All was going swimmingly until the drive I just added (3rd total drive, second non-virtual drive) to the NAS failed. I mean it disappeared from Windows as well as VMWare barfing. After that FreeNAS refuses to boot past Mounting local file systems, and eventually VMWare complains that the operation on the Physical Drive failed.
Since I couldn't get the system to boot at all, I removed the failed drive, but now Nothing Works... Sorry. Being hyperbolic. The Virtual machine will boot without the drive, but the FreeNAS GUI shows a status of Unknown, and zpool status says no pools available. When I do zpool import -f I get:
pool: Storage
id: 12192648677279661521
state: UNAVAIL
status: One or more drives are missing from the system
action: The pool cannot be imported. Attach the missing devices and try again.
I have only the one Volume -- "Storage". And I can't seen any way to remove the failed drive in the Volume section of the GUI. That's as far as I've gotten so far. I have installed a new hard drive to replace the failed one, but I haven't added it to the FreeNAS virtual machine yet. If you need any more info, just let me know.
--Phlod