Rsync of LVM Snapshots copies whole file

[Matt McCutchen]

On Tue, 2008-08-26 at 15:02 +0200, Peter P GMX wrote:
> does nobody has a clue about this?

As Paul said, the bottleneck appears to be disk I/O rather than network
bandwidth, so you should not expect any speedup from the delta-transfer
algorithm.  (Even though only 3% of the data differs, rsync needs to
read the entire source and destination images from disk to determine
that.)  --inplace and/or --whole-file might help reduce the disk I/O.

Matt

> Peter P GMX schrieb:
> > Hello Paul,
> >
> > here is the status of the transfer.
> > If I understand it right, about 3% of the data was changed (literal 
> > data against matched data). It took about 1h40min to transfer ~250MB 
> > of data.
> > But to be honest, I do not get a real clue out of this status report.
> > E.g. Laptop_D_10GB.vdi takes around 25 minutes to be transferred with 
> > 6,74MBytes/sec. If I divide 10G by 6,74MBytes/sec (for a complete file 
> > transfer) I end up at 40 minutes. So almost half of the complete data 
> > transfer time of this volume is needed, although this drive is rather 
> > passive and there were almost no changes on the drive between the last 
> > sync. (The machines are a AMD X2 3800 on one originating side and a 
> > Atom 1,6GHz on the destination side, Atom pulls from AMDs side).
> >
> > Best regards
> > Peter
> >
> > receiving file list ...
> > 13 files to consider
> > mit_backup/Debian40.vdi
> >  1395660800 100%    5.66MB/s    0:03:55 (xfer#1, to-check=11/13)
> > mit_backup/Laptop_D_10GB.vdi
> > 10734313984 100%    6.74MB/s    0:25:19 (xfer#2, to-check=10/13)
> > mit_backup/RubyServer_1_9GB.vdi
> >  2039489024 100%    8.15MB/s    0:03:58 (xfer#3, to-check=8/13)
> > mit_backup/XXXX_web.vdi
> >  2874171904 100%    6.17MB/s    0:07:24 (xfer#4, to-check=7/13)
> > mit_backup/Ubuntu_8_04_Development.vdi
> >  4367340032 100%    6.80MB/s    0:10:12 (xfer#5, to-check=6/13)
> > mit_backup/Ubuntu_XXXX_3GB.vdi
> >  3221238272 100%    5.61MB/s    0:09:07 (xfer#6, to-check=5/13)
> > mit_backup/W2000_6GB.vdi
> >  6442476032 100%    7.49MB/s    0:13:39 (xfer#7, to-check=4/13)
> > mit_backup/XXXXXXXX.vdi
> >  4294984192 100%    8.05MB/s    0:08:28 (xfer#8, to-check=3/13)
> >
> > Number of files: 13
> > Number of files transferred: 8
> > Total file size:             47.710.416.177 bytes
> > Total transferred file size: 35.369.674.240 bytes
> > Literal data:  1.181.132.240 bytes
> > Matched data: 34.188.542.000 bytes
> > File list size: 530
> > File list generation time: 0.001 seconds
> > File list transfer time: 0.000 seconds
> > Total bytes sent: 3.984.972
> > Total bytes received: 249.776.322
> >
> > sent 3.984.972 bytes  received 249.776.322 bytes  41515.14 bytes/sec
> > total size is 47.710.416.177  speedup is 188.01
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