> RAIDz does not let you do this: Start from one disk, add another disk > to mirror the data, add another disk to make it a RAIDz array, and add > another disk to increase the size of the RAIDz array.
That's true: today you can't expand a RAID-Z stripe or 'promote' a mirror to be a RAID-Z stripe. Given the current architecture, I'm not sure how that would be done exactly, but it's an interesting though experiment. How do other systems work? Do they take the pool offline while they migrate data to the new device in the RAID stripe or do they do this online? How would you propose this work with ZFS? Adam -- Adam Leventhal, Solaris Kernel Development http://blogs.sun.com/ahl
