I'm going to build a ZFS file server from FreeBSD. I learned recently that I can't expand a RAIDZ udev once it's part of the pool. That's a problem since I'm a home user and will probably add one disk a year tops.

But what if I set copies=3 against my entire pool and just throw individual drives into the pool separated? I've read somewheres that the copies will try and distribute across drives if possible. Is there a guarantee there? I really just want protection from bit rot and drive failure on the cheap. Speed's not an issue since it'll go over a 1Gb network and at MOST stream 720p podcasts.

Would my data be guaranteed safe from a single drive failure? Are there things I'm not considering? Any and all input is appreciated.