Hello, xfs never stops impressing me. Most if not all of my storage has been converted to it, including a 30TB+ unRaid server. I have been contemplating snapshot and dedup enabled filesystems like btrfs and ZFS but couldn't justify the jump. The new xfs reflink feature seems a good addition and compromise to a stable and proven filesystem. I'm strongly considering using the experimental reflink feature for my new photo drive. This will be done in a controlled environment with multiple backups. Are there any general rules of conduct when working with a dedup filesystem, like never go above 80% disk usage or never trust df/dh results? Also is there any risk of trying to mount a reflink enabled xfs filesystem on an older kernel that doesn't know about it? I don't think I need it for the moment but would enabling rmapbt as well add any risk to the data integrity or impact performance? Can rmapbt be enabled later on an existing filesystem if required? Will rmpabt be only used to enhance filesystem recovery? I'm planning to use this reflink feature for instant local snapshots and then use my backup software of choice, borg, to keep a long time history of my work on a remote server. Since borg stores data in a dedup fashion I can also backup the reflink snapshots and they won't take additional space. The only drawback is that today borg need to hash all the files found in a reflink directory in order to find out about dedup blocks. I asked a question on the borg mailing list https://github.com/borgbackup/borg/issues/2743 and apparently it won't be an issue to add a feature to support XFS in order to identify the physical extents. Is rmapbt required for that? Alphazo -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
