Re: btrfs send/receive using generation number as source
On Fri, Apr 8, 2016 at 5:01 AM, Martin Steigerwald wrote: > Hello! > > As far as I understood, for differential btrfs send/receive – I didn´t use it > yet – I need to keep a snapshot on the source device to then tell btrfs send > to send the differences between the snapshot and the current state. > > Now the BTRFS filesystems on my SSDs are often quite full, thus I do not keep > any snapshots except for one during rsync or borgbackup script run-time. > > Is it possible to tell btrfs send to use generation number xyz to calculate > the difference? This way, I wouldn´t have to keep a snapshot around, I > believe. > > I bet not, at the time cause -c wants a snapshot. Ah and it wants a snapshot > of the same state on the destination as well. Well on the destination I let > the script make a snapshot after the backup so… what I would need is to > remember the generation number of the source snapshot that the script creates > to backup from and then tell btrfs send that generation number + the > destination snapshots. > > Well, or get larger SSDs or get rid of some data on them. Well if you can't even keep one ro snapshot around, it suggests you need more space. Otherwise the minimal strategy is: Yesterday's source has subvols: root.current root.20160406 So you'd do btrfs sub snap -r root.current root.20160407 btrfs send -p root.20160406 root.20160407 | btrfs receive xxx btrfs sub del root.20160406 Today it's btrfs sub snap -r root.current root.20160408 btrfs send -p root.20160407 root.20160408 | btrfs receive xxx btrfs sub del root.20160407 Tomorrow: btrfs sub snap -r root.current root.20160409 btrfs send -p root.20160408 root.20160409 | btrfs receive xxx btrfs sub del root.20160408 Locally you always have one snapshot to rollback to or make selective reflink copies of files from. -- Chris Murphy -- 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
Re: btrfs send/receive using generation number as source
On Fri, Apr 8, 2016 at 1:01 PM, Martin Steigerwald wrote: > Hello! > > As far as I understood, for differential btrfs send/receive – I didn´t use it > yet – I need to keep a snapshot on the source device to then tell btrfs send > to send the differences between the snapshot and the current state. During the incremental send operation you need 2 ro snapshots available (a parent and a current snapshot) and after that, you just need to keep the current one and promote that to parent snapshot and keep it around until the next incremental send. So indeed that locks space and you might run out of free space if there is a long time before the next incremental send|receive and changes in the filesystem are large in volume. Alternatively, you could do non-incremental send, if the fs is relatively small and you have some method to dedupe on the receiving filesystem. But the rsync method is by far preferred in this case I would say. > Now the BTRFS filesystems on my SSDs are often quite full, thus I do not keep > any snapshots except for one during rsync or borgbackup script run-time. > > Is it possible to tell btrfs send to use generation number xyz to calculate > the difference? This way, I wouldn´t have to keep a snapshot around, I > believe. > > I bet not, at the time cause -c wants a snapshot. Ah and it wants a snapshot > of the same state on the destination as well. Well on the destination I let > the script make a snapshot after the backup so… what I would need is to You can use -p for incremental send and you can also send back (new) increments from backup to master. > remember the generation number of the source snapshot that the script creates > to backup from and then tell btrfs send that generation number + the > destination snapshots. > > Well, or get larger SSDs or get rid of some data on them. I switched from ext4 to btrfs rootfs on an old netbook which has only 4G soldered flash and no option for extension (except via USB/SDcard which turned out to be not reliable enough over a longer period of time). Basically compress=lzo mount option extents the lifetime of this netbook while still using a modern full-sized linux distro. But I guess you have already compressed/compacted what is possible. -- 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
Re: btrfs send/receive using generation number as source
On Freitag, 8. April 2016 11:12:54 CEST Hugo Mills wrote: > On Fri, Apr 08, 2016 at 01:01:03PM +0200, Martin Steigerwald wrote: > > Hello! > > > > As far as I understood, for differential btrfs send/receive – I didn´t use > > it yet – I need to keep a snapshot on the source device to then tell > > btrfs send to send the differences between the snapshot and the current > > state. > > > > Now the BTRFS filesystems on my SSDs are often quite full, thus I do not > > keep any snapshots except for one during rsync or borgbackup script > > run-time. > > > > Is it possible to tell btrfs send to use generation number xyz to > > calculate > > the difference? This way, I wouldn´t have to keep a snapshot around, I > > believe. > >btrfs sub find-new > >BUT that will only tell you which files have been added or updated. > It won't tell you which files have been deleted. It's also unrelated > to send/receive, so you'd have to roll your own solution. I am aware of this one. > > I bet not, at the time cause -c wants a snapshot. Ah and it wants a > > snapshot of the same state on the destination as well. Well on the > > destination I let the script make a snapshot after the backup so… > > what I would need is to remember the generation number of the source > > snapshot that the script creates to backup from and then tell btrfs > > send that generation number + the destination snapshots. > > > > Well, or get larger SSDs or get rid of some data on them. > >Those are the other options, of course. Hm, I see. Thanks, -- 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
Re: btrfs send/receive using generation number as source
On Fri, Apr 08, 2016 at 01:01:03PM +0200, Martin Steigerwald wrote: > Hello! > > As far as I understood, for differential btrfs send/receive – I didn´t use it > yet – I need to keep a snapshot on the source device to then tell btrfs send > to send the differences between the snapshot and the current state. > > Now the BTRFS filesystems on my SSDs are often quite full, thus I do not keep > any snapshots except for one during rsync or borgbackup script run-time. > > Is it possible to tell btrfs send to use generation number xyz to calculate > the difference? This way, I wouldn´t have to keep a snapshot around, I > believe. btrfs sub find-new BUT that will only tell you which files have been added or updated. It won't tell you which files have been deleted. It's also unrelated to send/receive, so you'd have to roll your own solution. > I bet not, at the time cause -c wants a snapshot. Ah and it wants a > snapshot of the same state on the destination as well. Well on the > destination I let the script make a snapshot after the backup so… > what I would need is to remember the generation number of the source > snapshot that the script creates to backup from and then tell btrfs > send that generation number + the destination snapshots. > Well, or get larger SSDs or get rid of some data on them. Those are the other options, of course. Hugo. -- Hugo Mills | The trouble with you, Ibid, is you think you know hugo@... carfax.org.uk | everything. http://carfax.org.uk/ | PGP: E2AB1DE4 | signature.asc Description: Digital signature
btrfs send/receive using generation number as source
Hello! As far as I understood, for differential btrfs send/receive – I didn´t use it yet – I need to keep a snapshot on the source device to then tell btrfs send to send the differences between the snapshot and the current state. Now the BTRFS filesystems on my SSDs are often quite full, thus I do not keep any snapshots except for one during rsync or borgbackup script run-time. Is it possible to tell btrfs send to use generation number xyz to calculate the difference? This way, I wouldn´t have to keep a snapshot around, I believe. I bet not, at the time cause -c wants a snapshot. Ah and it wants a snapshot of the same state on the destination as well. Well on the destination I let the script make a snapshot after the backup so… what I would need is to remember the generation number of the source snapshot that the script creates to backup from and then tell btrfs send that generation number + the destination snapshots. Well, or get larger SSDs or get rid of some data on them. Thanks, -- 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
