You seem pretty uninformed about ZFS so I'll try and help. As other have mentioned, there's the zpool scrub command which checks the integrity of the drive.
Also, I'm not sure where you got the "ZFS keeps previous versions of files around" idea from, it only does that if you make a snapshot, and only modifications of the file cause the file to be copied; this is waht copy on write is. It means you can have the whole history of your file system with almost no space overhead except for changes. Apple's time Machine does the same thing, but in a different way: each directory that hasn't been changed since the last backup is hard linked to the previous backup's version (which might itself be a hardlink). this makes is quite space efficient (and a pretty easy to understand hack to get versioning on a file system that doesn't natively support snapshots)
Also, I'm not sure where you got the "ZFS keeps previous versions of files around" idea from, it only does that if you make a snapshot, and only modifications of the file cause the file to be copied; this is waht copy on write is. It means you can have the whole history of your file system with almost no space overhead except for changes. Apple's time Machine does the same thing, but in a different way: each directory that hasn't been changed since the last backup is hard linked to the previous backup's version (which might itself be a hardlink). this makes is quite space efficient (and a pretty easy to understand hack to get versioning on a file system that doesn't natively support snapshots)