How does scp differ from rsync

Question

An article about setting up Ghost blogging says to use scp to copy from my local machine to a remote server   scp -r ghost-0 3 root  your-server-ip       However  Railscast 339  Chef Solo Basics uses scp to copy in the opposite direction  from the remote server to the local machine    scp -r root 178 xxx xxx xxx  var chef     In the same Railscast  when the author wants to copy files to the remote server  same direction as the first example   he uses rsync   rsync -r   root 178 xxx xxx xxx  var chef   Why use the rsync command if scp will copy in both directions  How does scp differ from rsync

User · Answer

scp is best for one file  OR a combination of tar  amp  compression for smaller data sets like source code trees with small resources  ie  images  sqlite etc     Yet  when you begin dealing with larger volumes say    media folders  40 GB  database backups  28 GB  mp3 libraries  100 GB     It becomes impractical to build a zip tar gz file to transfer with scp at this point do to the physical limits of the hosted server   As an exercise  you can do some gymnastics like piping tar into ssh and redirecting the results into a remote file   saving the need to build a swap or temporary clone aka zip or tar gz   However   rsync simplify s this process and allows you to transfer data without consuming any additional disc space   Also    Continuous  cron   updates use minimal changes vs full cloned copies speed up large data migrations over time    tl dr  scp      small scale  with room to build compressed files on the same drive   rsync    large scale  with the necessity to backup large data and no room left

User · Answer

rysnc can be useful to run on slow and unreliable connections  So if your download aborts in the middle of a large file rysnc will be able to continue from where it left off when invoked again   Use rsync -vP username host  path to file    The -P option preserves partially downloaded files and also shows progress   As usual check man rsync

User · Answer

One major feature  of rsync over scp  beside the delta algorithm and encryption if used w  ssh  is that it automatically verifies if the transferred file has been transferred correctly  Scp will not do that  which occasionally might result in corruption when transferring larger files  So in general rsync is a copy with guarantee   Centos manpages mention this the end of the --checksum option description      Note that rsync always verifies that each transferred file was   correctly reconstructed on the receiving side by checking a whole-file   checksum that is generated as the file is transferred  but that   automatic after-the-transfer verification has  nothing to do with this   option   s before-the-transfer    Does this file need to be updated       check

User · Answer

There s a distinction to me that scp is always encrypted with ssh  secure shell   while rsync isn t necessarily encrypted  More specifically  rsync doesn t perform any encryption by itself  it s still capable of using other mechanisms  ssh for example  to perform encryption   In addition to security  encryption also has a major impact on your transfer speed  as well as the CPU overhead   My experience is that rsync can be significantly faster than scp    Check out this post for when rsync has encryption on

User · Answer

Difference b w scp and rsync on different parameter  1  Performance over latency   scp   scp is relatively less optimise and speed rsync   rsync is comparatively more optimise and speed   https   www disk91 com 2014 technology networks compare-performance-of-different-file-transfer-protocol-over-latency   2  Interruption handling   scp   scp command line tool cannot resume aborted downloads from lost network connections rsync   If the above rsync session itself gets interrupted  you can resume it as many time as you want by typing the same command  rsync will automatically restart the transfer where it left off    http   ask xmodulo com resume-large-scp-file-transfer-linux html  3  Command Example  scp    scp source file path destination file path   rsync    cd  path to directory of partially downloaded file   rsync -P --rsh ssh userid remotehost com bigdata tgz   bigdata tgz    The -P option is the same as --partial --progress  allowing rsync to work with partially downloaded files  The --rsh ssh option tells rsync to use ssh as a remote shell   4  Security    scp is more secure  You have to use rsync --rsh ssh to make it as secure as scp   man document to know more     scp   http   www manpagez com man 1 scp  rsync   http   www manpagez com man 1 rsync

User · Answer

The major difference between these tools is how they copy files   scp basically reads the source file and writes it to the destination  It performs a plain linear copy  locally  or over a network   rsync also copies files locally or over a network  But it employs a special delta transfer algorithm and a few optimizations to make the operation a lot faster  Consider the call   rsync A host B    rsync will check files sizes and modification timestamps of both A and B  and skip any further processing if they match  If the destination file B already exists  the delta transfer algorithm will make sure only differences between A and B are sent over the wire  rsync will write data to a temporary file T  and then replace the destination file B with T to make the update look  atomic  to processes that might be using B    Another difference between them concerns invocation  rsync has a plethora of command line options  allowing the user to fine tune its behavior  It supports complex filter rules  runs in batch mode  daemon mode  etc  scp has only a few switches   In summary  use scp for your day to day tasks  Commands that you type once in a while on your interactive shell  It s simpler to use  and in those cases rsync optimizations won t help much   For recurring tasks  like cron jobs  use rsync  As mentioned  on multiple invocations it will take advantage of data already transferred  performing very quickly and saving on resources  It is an excellent tool to keep two directories synchronized over a network   Also  when dealing with large files  use rsync with the -P option  If the transfer is interrupted  you can resume it where it stopped by reissuing the command  See Sid Kshatriya s answer

User · Answer

it s better to think in a practical context  In our team  we use rsync -aP to replace a bad cassandra host in our cluster  We can t do this with scp  slow and no progress preservation

[rsync] How does `scp` differ from `rsync`?

Examples related to rsync

Examples related to scp