> This is practically the holy grail of "dynamic raid" - the ability to > dynamically use different redundancy settings on a per-directory > level, and to use a mix of different sized devices and add/remove them > at will.
Well I suspect that arbitrary redundancy configuration is not something we'll see anytime soon, nor is it something we should necessarily want. The main reason being it's very difficult to see it being used effectively; it's difficult enough to reason about data loss characteristics currently. (Not even considering the implementation complexity.) If you really need different guarantees on integrity, you could create separate specialized pools of mirrors -- or use the ditto blocks feature. As Richard Elling points out (http://blogs.sun.com/relling/entry/raid_recommendations_space_vs_mttdl), some redundancy (RAID-Z) is much better than none, and mirroring your data increases the MTTDL by another 5/6 orders of magnitude (though ditto'ing isn't quite doing that), and interestingly the RAID data points clump together. I think the important thing is that the system should be a little more flexible than it is currently (allow variably sized disks, adding/removing them), but not so much so that it's a completely different system. James _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
