Date: Tue, 13 Dec 2016 15:44:58 -0800 From: Aleksandr Miroslav <alexmiroslav@gmail.com> To: freebsd-questions@freebsd.org Subject: zfs (zxfer) replication -- "holes" in backups? Message-ID: <CACcSE1xb1k330wJ6tyvQ2Vfv8bFKT97cbDx=OQaES8V8pOQ9DA@mail.gmail.com>
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I'm using zxfer to replicate my ZFS snapshot to another host. Occasionally, for whatever reason, zxfer can't replicate a particular snapshot. What I find is that later when zxfer tries again, it skips that snapshot it couldn't replicate and sends a newer one. This leaves the back up server with with a "hole", i. e. a missing snapshot. For example: I have server with the following snapshots: *zroot/usr/home@zfs-auto-snap_daily-2016-11-19-00h00 [EXISTS ON BACKUP]zroot/usr/home@zfs-auto-snap_weekly-2016-11-20-00h00 [EXISTS ON BACKUP]zroot/usr/home@zfs-auto-snap_daily-2016-11-21-00h00 [EXISTS ON BACKUP]zroot/usr/home@zfs-auto-snap_daily-2016-11-22-00h00 [EXISTS ON BACKUP]zroot/usr/home@zfs-auto-snap_daily-2016-11-23-00h00 [MISSING BACKUP][...]zroot/usr/home@zfs-auto-snap_hourly-2016-12-13-14h00 [MISSING BACKUP]zroot/usr/home@zfs-auto-snap_hourly-2016-12-13-15h00 [EXISTS ON BACKUP]* Here is my backup server: *zroot/usr/home@zfs-auto-snap_daily-2016-11-19-00h00* *zroot/usr/home@zfs-auto-snap_weekly-2016-11-20-00h00* *zroot/usr/home@zfs-auto-snap_daily-2016-11-21-00h00* *zroot/usr/home@zfs-auto-snap_daily-2016-11-22-00h00* *zroot/usr/home@zfs-auto-snap_hourly-2016-12-13-15h00* Notice that I have backups until the 22nd of November, and there is a huge gap until the 13th of December. Usually these gaps are small, one or two missing snapshots...in this particular case, the backup server was offline for a bit. When zxfer starts up again, I thought it would resume sending from the last one, it apparently doesn't do that. The way I have fixed this manually in the past is to delete the newest backup on the target server and run zxfer manually. Recently, the missing backups have gotten so large that this is somewhat painful to do. Is there something in zfs/zxfer I can change such that the backup server will always have the latest copy as the master? thanks, Alex
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