On 16/05/14 04:07, Russell Coker wrote: > https://blogs.oracle.com/bill/entry/ditto_blocks_the_amazing_tape > > Probably most of you already know about this, but for those of you who > haven't > the above describes ZFS "ditto blocks" which is a good feature we need on > BTRFS. The briefest summary is that on top of the RAID redundancy there... [... are additional copies of metadata ...]
Is that idea not already implemented in effect in btrfs with the way that the superblocks are replicated multiple times, ever more times, for ever more huge storage devices? The one exception is for SSDs whereby there is the excuse that you cannot know whether your data is usefully replicated across different erase blocks on a single device, and SSDs are not 'that big' anyhow. So... Your idea of replicating metadata multiple times in proportion to assumed 'importance' or 'extent of impact if lost' is an interesting approach. However, is that appropriate and useful considering the real world failure mechanisms that are to be guarded against? Do you see or measure any real advantage? Regards, Martin -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
