With --backup in order to end up with 2 files it has to write out a whole new file. Sure, it only sent the differences (normally that means over the network but there is no network here) but the writing end was told to duplicate the file being updated before updating it.
On 2/13/19 10:47 AM, Delian Krustev via rsync wrote:
> Hi All,
>
> For a backup purpose I'm trying to transfer only the changed blocks of
> large files. Thus I've run "rsync" with the appropriate options:
>
> RSYNC_BKPDIR=`mktemp -d`
> rsync \
> --archive \
> --no-whole-file \
> --inplace \
> --backup \
> --backup-dir="$RSYNC_BKPDIR" \
> --verbose \
> --stats \
> /var/backups/mysql-dbs/. \
> /mnt/bkp/var/backups/mysql-dbs/.
>
> The problem is that although "rsync" shows that delta transfer is used(when
> run with -vv) and only small amount if data is transferred, the target files
> look to be overwritten in full.
>
> Here is the output of "rsync" and some more debugging info:
>
>
> ####################################################
> sending incremental file list
> ./
> horde.data.sql
> horde.schema.sql
> LARGEDB.data.sql
> LARGEDB.schema.sql
> mysql.data.sql
> mysql.schema.sql
> phpmyadmin.data.sql
> phpmyadmin.schema.sql
>
> Number of files: 9 (reg: 8, dir: 1)
> Number of created files: 0
> Number of deleted files: 0
> Number of regular files transferred: 8
> Total file size: 1,944,522,704 bytes
> Total transferred file size: 1,944,522,704 bytes
> Literal data: 21,421,681 bytes
> Matched data: 1,923,101,023 bytes
> File list size: 0
> File list generation time: 0.001 seconds
> File list transfer time: 0.000 seconds
> Total bytes sent: 21,612,218
> Total bytes received: 323,302
>
> sent 21,612,218 bytes received 323,302 bytes 259,591.95 bytes/sec
> total size is 1,944,522,704 speedup is 88.65
>
> # du -m 1.9G /tmp/tmp.8gBzjNQOQZ
> 1.9G /tmp/tmp.8gBzjNQOQZ
>
> # tree -a /tmp/tmp.8gBzjNQOQZ
> /tmp/tmp.8gBzjNQOQZ
> ├── horde.data.sql
> ├── horde.schema.sql
> ├── LARGEDB.data.sql
> ├── LARGEDB.schema.sql
> ├── mysql.data.sql
> ├── mysql.schema.sql
> ├── phpmyadmin.data.sql
> └── phpmyadmin.schema.sql
>
> 0 directories, 8 files
>
> Free space at the beginning and end of the backup:
> Filesystem 1M-blocks Used Available Use% Mounted on
> /dev/mapper/bkp 102392 76872 20400 80% /mnt/bkp
> /dev/mapper/bkp 102392 78768 18504 81% /mnt/bkp
>
> ####################################################
>
> As can be seen "rsync" has sent about 20M and received 300K of data. However
> the filesystem has allocated almost 2G, which is the total size of the files
> being backed up.
>
> The filesystem mounted on "/mnt/bkp" is of type "nilfs2", which is a log
> structured filesystem. I'm using its snapshotting feature to keep backups for
> past dates.
>
>
> Is there anything that can be done in order "rsync" to overwrite only the
> changed blocks ?
>
>
>
>
> P.S. I guess that it will be the same for copy-on-write filesystems, e.g.
> BTRFS or ZFS.
>
>
>
> Cheers
> --
> Delian
>
--
~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,
Kevin Korb Phone: (407) 252-6853
Systems Administrator Internet:
FutureQuest, Inc. ke...@futurequest.net (work)
Orlando, Florida k...@sanitarium.net (personal)
Web page: https://sanitarium.net/
PGP public key available on web site.
~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,
signature.asc
Description: OpenPGP digital signature
-- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
