Received: (at submit) by bugs.debian.org; 1 Feb 2001 02:25:09 +0000 From screechco@home.com Wed Jan 31 20:25:09 2001 Return-path: Received: from femail8.sdc1.sfba.home.com [::ffff:24.0.95.88] by master.debian.org with esmtp (Exim 3.12 1 (Debian)) id 14O9Qq-0007U9-00; Wed, 31 Jan 2001 20:25:08 -0600 Received: from brooks.homenet ([24.18.239.121]) by femail8.sdc1.sfba.home.com (InterMail vM.4.01.03.00 201-229-121) with ESMTP id <20010201022507.GVLT26894.femail8.sdc1.sfba.home.com@brooks.homenet> for ; Wed, 31 Jan 2001 18:25:07 -0800 Received: from localhost ([127.0.0.1] helo=brooks ident=danish) by brooks.homenet with esmtp (Exim 3.22 #1 (Debian)) id 14O9Ys-00010n-00 for ; Wed, 31 Jan 2001 21:33:26 -0500 X-Mailer: exmh version 2.2 06/23/2000 (debian 2.2-1) with nmh-1.0.4+dev From: Chris Danis To: submit@bugs.debian.org Subject: for speeding up partial downloads Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 31 Jan 2001 21:33:26 -0500 Message-Id: Delivered-To: submit@bugs.debian.org Package: rsync Severity: wishlist Many times, when one is downloading a large file, the transfer gets interrupted for one reason or another. What if rsync could: 1) Compare file sizes between server and client, and for whichever one is smaller (call this computer A), look at that much of the file on the end with the larger file (call this computer B). In other words, take computer A's file and compare the md5sum (or initially, Adler32) against the first however many bytes of computer's B file (as determined by filesize on computer A). This treats the portion of the file already on computer A as one chunk, meaning only one checksum must be computed and sent over the wire. Possibly, rsync (on each end) could internally still break it apart, to take advantage of redundancies (but even with this, checksums of these internally-computed blocks do not have to be sent over the wire). 2) If they match, continue onwards (with the normal blocksize and whatnot) from that point. This could save much time(/bandwidth) computing, sending, and comparing lots of small checksums. If they don't match, rsync can just work as normal. -chris -- "Meat. They're made out of meat." "It's better than bad, it's good!" (I subscribe to all lists that I post to; please do not Cc me) Chris Danis screech@mad.scientist.com screechco@home.com dadanish@usa.net