>> I think I leave it as is for the time being, unless there is some news >> how to fix things with low risk (or maybe via a temp overlay snapshot >> with DM). But the lowmem check took 2 days, that's not really fun. >> The goal for the 8TB fs is to have an up to 7 year snapshot history at >> sometime, now the oldest snapshot is from early 2014, so almost >> halfway :) > > Btrfs is still much too unstable to trust 7 years worth of backup to > it. You will probably loose it at some point, especially while many > snapshots are still such a huge performance breaker in btrfs. I suggest > trying out also other alternatives like borg backup for such a project.
Maybe I should clarify that I don't use snapshotting for archiving explicitly. So in the latest snapshot still old but unused files from many years back are there, like a disk image from a windowsxp laptop (already recycled) for example. Userdata that is in older snapshots but not in newer ones is what I consider useless data today, so I had deleted that explicitly. But who knows maybe for some statistic or whatever btrfs experiment it might be interesting to have a long and may snapshot increments. Another reason is the SMR characteristics of the disk, that made me decide to designate this fs write-only. If I remove snapshots, the fs gets free space fragmentation and then writing to it will be much slower. This disk was relatively cheap and I don't want to experience the slowness and longer on time. I snapshot no more than 3 subvolumes monthly, then after 7 years the fs has 252 snapshots, that is considered no problem for btrfs. I think borg backup is interesting, but from kernel 3.11 to 4.11 (even using raid5 up to 4.1) I have managed to keep it running/cloning multi-site with just a few relatively simple scripts and btrfs kernel+tools itself, also working on a low-power ARM platform. I don't like yet another commandset and that borg uses its own extra repo or small database for tracking diffs (I haven't used it so I am not sure). But what I need, differential/incremental + compression, is just build-in in btrfs, that I anyhow use for local snapshotting. I finally put also some ARM boards btrfs rootfs recently, I am not sure if/when I am going to use other backup tooling besides just rsync and btrfs features. -- 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
