I want to know the default speed of rsync command to send data from local machine to remote machine. Is that depend on network or rsync has default speed is set for rsync command.
2 Answers
The default speed depends on the network, and on the system.
If not explicitly asked for, rsync
will try to use all the available bandwidth.
Nevertheless you can read a speed value higher then the physical bandwidth of your connection because the counts of the speedup value is probably made dividing the total amount of data for the used time; note the "total amount of data" and not the "total amount of data transferred". This is even more evident when you do a dry-run with the -n
option specified to perform a trial run that will not make any change.
Indeed rsync
can skips files or part of the files in the transfer operation when it is not needed to update them following the current options.
Rsync finds files that need to be transferred using a "quick check" algorithm (by default) that looks for files that have changed in size or in last-modified time. Any changes in the other preserved attributes (as requested by options) are made on the destination file directly when the quick check indicates that the file’s data does not need to be updated.
Option that can affect the normal use (see below) are
--bwlimit=RATE limit socket I/O bandwidth
Note that since rsync can also be run as a daemon
this option is accepted in both cases client and demon.
-W, --whole-file With this option rsync’s delta-transfer algorithm is not
used and the whole file is sent as-is instead.
About -W
The transfer may be faster if this option is used when the bandwidth between the source and destination machines is higher than the bandwidth to disk (especially when the "disk" is actually a networked filesystem). This is the default when both the source and destination are specified as local paths, but only if no batch-writing option is in effect.
Note: it is always possible (even if not probable) that your system is limiting the bandwidth for the processes (see for example [1]) or the host system in the case of VirtualBox or Windows+Cygwin is putting some limits or delay due to different operations (sniffing, antivirus...)
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can you give me more discription about windows+cygwin for delay in rsync– LOKESHNov 16, 2015 at 8:42
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1With Cygwin you share part of the windows HD with the Cygwin environment. Even if you use
rsync
from the Cygwin commandline, those files are always subject to the control of the hosting operative system. If in windows there is an antivirus active (as it is usual) those files will be scanned by it (if they have to, of course). If a temporary file is created, even this one can be scanned by the antivirus... If there is some utility that organizes the filesystem it can decide to change their position... and so on...– HasturNov 16, 2015 at 9:39 -
Read from the manual of
rsync
the option--inplace
and--append
. They can change the overall speed of the transfer, even more if there is an antivirus on the windows destination...– HasturNov 16, 2015 at 9:43 -
I'm not sure if rsync can't or won't use all available bandwidth, but
rsync will try to use all the available bandwidth
is not true. Don't believe me? Compare performance of rsync with bbcp. Dec 5, 2016 at 21:00 -
@JamesShewey
rsync
differs frombbcp
.bbcp
is more similar toscp
. BTW I trust that in SLAC/cern collaboration they developed tools efficient with huge data transfer (we have internet thanks to the particle physics needs...) and it is a nice spot to a (still) less known tool...– HasturDec 6, 2016 at 7:23
I don't think rsync
have a default speed. Most of the time rsync
is used with ssh and speed over scp
will be same as rsync
--bwlimit
option).