> rsync is saving bandwidth at the cost of processing overhead doesnt mean that > rsync > is just for this purpose, it is a way to think about it. Dont be so single > minded. > > As a matter of fact the rsync page says 'rsync is an open source > utility that provides fast incremental file transfer.' and I want speed which > coincides with the statement in rsync web pages. > > Just something that needs pointing out here, is that rsync is only a "fast incremental file transfer" program when transferring large files over a slow link. The rsync protocol reads the files at both ends, compares them blocks at a time with checksums, then writes out a whole new copy of each file. For a slow link this is great, as the data transferred is a little bigger than the differences in the file, so a 1Gb file with 1 byte changed at the end only has to transfer that 1 byte plus all the checksums etc. For a fast link this is actually slower, as both ends have to read the file, compute checksums, communicate them to each other, transfer chunks of the file down the line, then the destination server has to write out the file after applying the difference patch. For fast links it is much faster for the system to read at one end and write at the other, transferring large chunks without using any cpu power. And for completely new or completely changed files (think a gzip'd file) this actually means rsync is slower and transfers more data!
So in the case where is says it's a fast incremental file transfer, it's still saying you're saving bandwidth (read that as time on a slow link and therefore is faster) at the expense of processing overhead. Just had to clear that misunderstanding up. Josh. P.S. If you're using rsync over ssh then make sure you use the blowfish cipher - it's much much faster than the default. I personally use rsyncd as it's on a trusted network and don't want the encryption overhead of ssh. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ BackupPC-users mailing list BackupPC-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/backuppc-users http://backuppc.sourceforge.net/
