Anyone using freebsd ZFS for large storage servers?

[Wojciech Puchar]

>> level?
>>
>>
>
> It was my impression that ZFS doesn't actually format the disk as

does any filesystem "format" a disk?
disks are nowadays factory formatted.

filesystem only write data and it's metadata on it.

I really recommend you to get basic knowledge of how (any) filesystem 
works.

THEN please discuss things.