On 11/02/2016 03:23 PM, René Bühlmann wrote: > > I have a system running on btrfs which is backed up to two (one local > USB and one through SSH) external drives (also using btrfs) using > send/receive (with the help of btrbk). For each backup a snapshot is > created and transferred to the external drives. After some time, the > snapshot on the origin is removed but kept on the two backups. > > Now my problem is, that the SSH-drive has not received any snapshots for > some time such that there is no snapshot any more which is on the origin > AND the SSH-drive. I would like to prevent transferring a full snapshot > over the network and am now trying to work around it. > > Here the current situation (S? for a Snapshot): > > Origin: S2 S3 > > USB: S1 S2 > > SSH: S1 > > Transferring S3 to USB is no problem as S2 is on both btrfs drives. But > how can I transfer S3 to SSH? Since there is no snapshot left that is present on both drives, you cannot use incremental send. btrbk does not remember what snapshots were last transferred or were present on the missing disk, since the tool does not do any extra meta administation on top of just having the snapshots on btrfs level. So it's figuring out the relationships between each of them (combining it with info from the remotes) again every time it runs. > I tried to transfer... > > 1. S3 from Origin to SSH -> does not work as there is no common snapshot. > > 2. S2 from USB to SSH -> did not work. > > 3. S1 from USB to Origin (such that there is a common snapshot with SSH) > -> did not work. > > Is it correct that 1. would work if a common snapshot is present on > Origin and SSH? > > Is it expected that 2. and 3. do not work? > > Is there some other way to achieve it? At home, I do a similar thing, I periodically send/receive changes of a filesystem to two external disks, also using btrbk. Since I don't want to have both backup disks and the originating filesystem all online and in the same geographical location at the same moment, I have the same problem. What I did is just setting expiry the snapshots on the origin manually, and keep the meta-administration in my head. I don't do it that often anyway. -- Hans van Kranenburg -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
