On 11.09.2012 01:38, Jan Engelhardt wrote: > > On Tuesday 2012-09-11 01:09, Martin Steigerwald wrote: >>>> What about: >>>> >>>> - copy first backup version >>>> - btrfs subvol create first next >>>> - copy next backup version >>>> - btrfs subvol create previous next >>> >>> Wouldn't "btrfs subvolume snapshot", plus "rsync --inplace" more >>> useful here? That is. if the original hardlink is caused by multiple >>> versions of backup of the same file. >> >> Sure, I meant subvol snapshot in above example. Thanks for noticing. >> >> But I do not use --inplace as it conflicts with some other rsync options I >> like to use: > > It is a tradeoff. > > rsync "--inplace" leads to fragmentation which is detrimental for the > speed of reads (and read-write-cycles as used by rsync) of big files > (multi-GB) that are regularly updated, but it is probably even worse > for smaller-than-GB files because percent-wise, they are even more > fragmented. > > $ filefrag */vm/intranet.dsk > snap-2012-08-15/vm/intranet.dsk: 23 extents found > snap-2012-08-16/vm/intranet.dsk: 23 extents found > snap-2012-08-17/vm/intranet.dsk: 4602 extents found > snap-2012-08-18/vm/intranet.dsk: 6221 extents found > snap-2012-08-19/vm/intranet.dsk: 6604 extents found > snap-2012-08-20/vm/intranet.dsk: 6694 extents found > snap-2012-08-21/vm/intranet.dsk: 6650 extents found > snap-2012-08-22/vm/intranet.dsk: 6760 extents found > snap-2012-08-23/vm/intranet.dsk: 7226 extents found > snap-2012-08-24/vm/intranet.dsk: 7159 extents found > snap-2012-08-25/vm/intranet.dsk: 7464 extents found > snap-2012-08-26/vm/intranet.dsk: 7746 extents found > snap-2012-08-27/vm/intranet.dsk: 8017 extents found > snap-2012-08-28/vm/intranet.dsk: 8145 extents found > snap-2012-08-29/vm/intranet.dsk: 8393 extents found > snap-2012-08-30/vm/intranet.dsk: 8474 extents found > snap-2012-08-31/vm/intranet.dsk: 9150 extents found > snap-2012-09-01/vm/intranet.dsk: 8900 extents found > snap-2012-09-02/vm/intranet.dsk: 9218 extents found > snap-2012-09-03/vm/intranet.dsk: 9575 extents found > snap-2012-09-04/vm/intranet.dsk: 9760 extents found > snap-2012-09-05/vm/intranet.dsk: 9839 extents found > snap-2012-09-06/vm/intranet.dsk: 9907 extents found > snap-2012-09-07/vm/intranet.dsk: 10006 extents found > snap-2012-09-08/vm/intranet.dsk: 10248 extents found > snap-2012-09-09/vm/intranet.dsk: 10488 extents found > > Without --inplace (prerequisite to use -S) however, it will recreate > a file if it has been touched. While this easily avoids fragmentation > (since it won't share any data blocks with the old one), it can take > up more space with the big files. > >> -ax --acls --xattrs --sparse --hard-links --del --delete-excluded -- > > I knew short options would be helpful here: -axAXSH > (why don't they just become the standard... they are in like almost > every other rsync invocation I ever had) > >> -S, --sparse >> Try to handle sparse files efficiently so they take up >> less space on the destination. Conflicts with --inplace >> because it’s not possible to overwrite data in a sparse >> fashion. > > Oh and if anybody from the rsync camp reads it: with hole-punching > now supported in Linux, there is no reason not to support "-S" with > "--inplace", I think.
I sent a patch for this quite some time ago: https://bugzilla.samba.org/show_bug.cgi?id=7194 Feel free to push it :) -Arne > -- > 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 -- 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
